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    <title>树莓派PICO入门教程</title>
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    <published>2022-12-26T16:21:25.042Z</published>
    <updated>2022-12-26T16:21:25.062Z</updated>
    
    <content type="html"><![CDATA[<p><a href="https://pico.org.cn/">树莓派 Pico 中文站</a></p><h1 id="1-板子介绍"><a href="#1-板子介绍" class="headerlink" title="1.板子介绍"></a>1.板子介绍</h1><p><img src="https://img-blog.csdnimg.cn/30fbdffa7f8247f399daaa6648710ccb.png" alt="![[Pasted image 20220920122543.png]]"></p><p>：</p><ul><li>微型usb连接器  microUSB    数据通信，提供动力</li><li>On-board LED 板载LED   在自己专用的GPIO端口    峰值上的唯一LED<br>不会给出电源任何施加到上面的指示</li><li>boot select按钮 启动模式选择  引导加载程序</li><li>Debug Pins 调试连接器   pico支持两线串行通过这个进行调试</li><li>rp2040微控制器芯片</li></ul><p><img src="https://img-blog.csdnimg.cn/d57ad3b8b77a4bceaa5a145827b5f810.png" alt="![[Pasted image 20220920122934.png]]"></p><ul><li>32位双核  arm-cortex m zero plus 芯片</li><li>以48兆赫的的正常时钟速度运行，并可提升至133兆赫</li><li>2兆字节的板载外部内存</li><li>板载实时时钟</li><li>板载温度传感器</li></ul><p><img src="https://img-blog.csdnimg.cn/cd59e636f640492f8850f927966acefc.png" alt="![[Pasted image 20220920123303.png]]"></p><ul><li>要么使用引脚，要么表面安装</li><li>8个接地点   其中一个是1个调试的一部分    接地点发布均匀</li><li>所有的接地连接是方行焊盘而不是圆形焊盘</li></ul><p><img src="https://img-blog.csdnimg.cn/06171eab73b445179912d3d2f07f0f74.png" alt="![[Pasted image 20220920124224.png]]"></p><ul><li>v总线和输出的微型usb电缆电压   连接5v    无连接v总线无输出   </li><li>系统的输入功率   可以在2到5v的电压下运行该系统   尽管pico是3.3v逻辑机</li><li>引脚36上的3.3输出是pico的内部电压调节器的3.3输出   可以用来驱动外部设备，但不要超过3亿</li><li>3.3伏使能可启用  扳上的3.3伏电源   可以外部打开或关闭</li><li>run连接     rp2040微控制器的使能连接    可以用作微控制器的复位</li></ul><p><img src="https://img-blog.csdnimg.cn/379e2633554d419d85451c59adda2244.png" alt="![[Pasted image 20220920124407.png]]"></p><ul><li>26个裸露的gpio引脚</li><li>内部的第27个TPIO引脚用于板载LED</li></ul><p><img src="https://img-blog.csdnimg.cn/27ea7d79ce0d4914a4a2afa45557886d.png" alt="![[Pasted image 20220920124735.png]]"></p><ul><li>12位模数转换器</li><li>3个内部模数转换器</li><li>内部ADC用于温度传感器</li><li>ADC vref   gnd   用于外部基准电压源    以提高模数转换器的精度</li></ul><p><img src="https://img-blog.csdnimg.cn/e0892157ce9a4318b0166db4986be3b3.png" alt="![[Pasted image 20220920125113.png]]"></p><ul><li>2个I2C总线</li><li>2个SPI总线</li><li>2个URAT</li><li>16个PWM通道</li></ul><p><img src="https://img-blog.csdnimg.cn/ab59e47948e04263bed21502f01da16d.png" alt="![[Pasted image 20220920125351.png]]"></p><ul><li>普通的微控制器运行</li><li>使用micro usb 端口通电</li><li>使用电池供电，能够在低压2伏特的电压下工作</li><li>作为usb 设备运行</li><li>micro python  或 c</li></ul><h1 id="2-led开关"><a href="#2-led开关" class="headerlink" title="2.led开关"></a>2.led开关</h1><p><img src="https://img-blog.csdnimg.cn/fb8eb87ebb2742ff9787992cd6312edb.png" alt="![[Pasted image 20220920131020.png]]"></p><ul><li>26个gpio引脚，大多数的引脚支持带调制的脉冲</li><li>3.3v的逻辑器件</li><li>内置上拉电阻和下拉电阻，最大限度的减少所需的电路数量</li></ul><p><img src="https://img-blog.csdnimg.cn/085626eae58645119f6e84c92802676b.png" alt="![[Pasted image 20220920132001.png]]"></p><p>可以用3个红绿蓝LED<br>或者一个LED</p><p>瞬间接触开关<br>一红一黑</p><p>3LED 需要3个降压电阻   330欧姆的电阻</p><p>引脚14（gpio引脚10）  连接到其中一个电阻器，连接到红色LED的阳极<br>引脚15（gpio引脚11）  连接到其中一个电阻器，连接到绿色LED的阳极<br>引脚19（gpio引脚14）  连接到其中一个电阻器，连接到蓝色LED的阳极</p><p>引脚23  上的接地点；连接到LED上的公共阴极</p><p>引脚4 （gpio引脚2）连接到黑色开关的一侧<br>引脚20 （gpio引脚15）连接到红色开关的一侧</p><p>引脚3 接地 连接到黑色开关的另一侧</p><p>pin引脚36   3.3v输出     连接到红色开关的另一侧</p><p>循环亮3种不同颜色</p><pre class="line-numbers language-python" data-language="python"><code class="language-python"><span class="token keyword">import</span> machine<span class="token keyword">import</span> utime<span class="token comment"># 对应引脚并打开输出</span>led_red <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>OUT<span class="token punctuation">)</span>led_green <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">11</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>OUT<span class="token punctuation">)</span>led_blue <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">14</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>OUT<span class="token punctuation">)</span><span class="token keyword">while</span> <span class="token boolean">True</span><span class="token punctuation">:</span>    led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>    led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span>     led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>    led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span>    led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>    utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span>    led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>    led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>    led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span>    led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>    led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>    utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span>    led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>    led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>    utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span>    led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>    led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>    led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>    utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span>    <span class="token keyword">print</span><span class="token punctuation">(</span><span class="token string">"End of Loop"</span><span class="token punctuation">)</span>    led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span> <span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><h1 id="4-开关控制："><a href="#4-开关控制：" class="headerlink" title="4.开关控制："></a>4.开关控制：</h1><pre class="line-numbers language-python" data-language="python"><code class="language-python"><span class="token keyword">import</span> machine  <span class="token keyword">import</span> utime    <span class="token comment">#时间有关的库</span>button_red <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">15</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>IN<span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>PULL_DOWN<span class="token punctuation">)</span>   <span class="token comment"># gpio15 输入 下拉电阻，因为红灯的</span>                                                                      <span class="token comment"># 的一段是3.3v 所以一直保持低位</span>                                                                      <span class="token comment"># 当开关接通时，它将激活并将其拉高</span>button_black <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>IN<span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>PULL_UP<span class="token punctuation">)</span>  <span class="token comment"># 上拉电阻，降低即开始</span><span class="token keyword">while</span> <span class="token boolean">True</span><span class="token punctuation">:</span>     <span class="token keyword">if</span> button_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">==</span> <span class="token number">1</span><span class="token punctuation">:</span>        <span class="token keyword">print</span><span class="token punctuation">(</span><span class="token string">"Red"</span><span class="token punctuation">)</span>     <span class="token keyword">if</span> button_black<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">==</span> <span class="token number">0</span><span class="token punctuation">:</span>        <span class="token keyword">print</span><span class="token punctuation">(</span><span class="token string">"Black"</span><span class="token punctuation">)</span>    utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">0.25</span><span class="token punctuation">)</span>  <span class="token comment"># 延迟</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><h1 id="5-中断："><a href="#5-中断：" class="headerlink" title="5.中断："></a>5.中断：</h1><pre class="line-numbers language-python" data-language="python"><code class="language-python"><span class="token keyword">import</span> machine<span class="token keyword">import</span> utimeled_red <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>OUT<span class="token punctuation">)</span>led_green <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">11</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>OUT<span class="token punctuation">)</span>led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>  <span class="token comment"># 关灯</span>button_red <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">15</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>IN<span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>PULL_DOWN<span class="token punctuation">)</span>   <span class="token comment"># 正常下拉电阻为低，除非按他就会拉高</span><span class="token keyword">def</span> <span class="token function">in_handler</span><span class="token punctuation">(</span>pin<span class="token punctuation">)</span>     button_red<span class="token punctuation">.</span>irq<span class="token punctuation">(</span>handler<span class="token operator">=</span><span class="token boolean">None</span><span class="token punctuation">)</span>  <span class="token comment"># 关闭此引脚的中断</span>     <span class="token keyword">print</span><span class="token punctuation">(</span><span class="token string">"Interrupt Detected!"</span><span class="token punctuation">)</span>     led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>      led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>      utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">4</span><span class="token punctuation">)</span>  <span class="token comment"># 休眠在中断不常见，这是个示范</span>     led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>     button_red<span class="token punctuation">.</span>irq<span class="token punctuation">(</span>handler<span class="token operator">=</span>int_handler<span class="token punctuation">)</span>  <span class="token comment"># 重新设置程序，然后才能再次工作</span>button_red<span class="token punctuation">.</span>irq<span class="token punctuation">(</span>trigger<span class="token operator">=</span>machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>IRQ_RISING<span class="token punctuation">,</span> handler<span class="token operator">=</span>int_handler<span class="token punctuation">)</span><span class="token comment"># 修复中断请求  触发中断  我们在上升信号时触发它（低到高）  此时传入一个被称为中断处理程序的函数</span><span class="token comment"># 每次按下按钮会有一个中断，就调用这个函数</span><span class="token comment"># 不被中断时</span><span class="token keyword">while</span> <span class="token boolean">True</span><span class="token punctuation">:</span>      led_green<span class="token punctuation">.</span>toggle<span class="token punctuation">(</span><span class="token punctuation">)</span>  <span class="token comment"># 切换函数 ，获取输出状态并将其反转</span>        <span class="token comment"># led将开或关，就反转成</span>      utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><h1 id="6-按按钮灯循环亮："><a href="#6-按按钮灯循环亮：" class="headerlink" title="6.按按钮灯循环亮："></a>6.按按钮灯循环亮：</h1><pre class="line-numbers language-python" data-language="python"><code class="language-python"><span class="token keyword">import</span> machine<span class="token keyword">import</span> utime<span class="token comment"># 对应引脚并打开输出</span>led_red <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>OUT<span class="token punctuation">)</span>led_green <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">11</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>OUT<span class="token punctuation">)</span>led_blue <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">14</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>OUT<span class="token punctuation">)</span>led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>button_black <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>IN<span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>PULL_UP<span class="token punctuation">)</span>  <span class="token comment"># 上拉电阻，降低即开始</span><span class="token keyword">while</span> <span class="token boolean">True</span><span class="token punctuation">:</span>     <span class="token keyword">if</span> button_black<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">==</span> <span class="token number">0</span><span class="token punctuation">:</span>   <span class="token comment">#  按下按钮，值为0</span>                led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>    led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>    led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>    led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>    led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>                led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    <span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><h1 id="7-模拟输入："><a href="#7-模拟输入：" class="headerlink" title="7.模拟输入："></a>7.模拟输入：</h1><p><img src="https://img-blog.csdnimg.cn/b1b576fd6bfc4c32b4884ce56c90f7ea.png" alt="![[Pasted image 20220920232711.png]]"></p><ul><li>3个内部模数转换器</li><li>12位adc</li><li>模拟基准电压源   模拟接地引脚     可与外部基准电压源配合使用</li></ul><p>最简单组件是有效直径</p><p>这里使用10k的直线壶</p><ul><li>引脚23  连接到patometer的一端</li><li>引脚31  gpio26   模拟转换器0  连接到patometer的一端</li><li>引脚36  3.3v输出   连接到patometer的一端</li></ul><p>代码</p><pre class="line-numbers language-python" data-language="python"><code class="language-python"><span class="token keyword">import</span> machine<span class="token keyword">import</span> utime<span class="token comment"># 定义一个称为电位计的变量，并将其定义为模拟输入，然后使用库的ADC功能</span>potentiometer <span class="token operator">=</span> machine<span class="token punctuation">.</span>ADC<span class="token punctuation">(</span><span class="token number">26</span><span class="token punctuation">)</span><span class="token keyword">while</span> <span class="token boolean">True</span><span class="token punctuation">:</span>    <span class="token keyword">print</span><span class="token punctuation">(</span>potentiometer<span class="token punctuation">.</span>read_u16<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span>   <span class="token comment"># 打印电位值，打印模数转换器的输出值</span>                                      <span class="token comment"># 使用的是读出无符号16位输出，16位实际从0到65535</span>                                      <span class="token comment"># 但是返回的值可能不是你期待的值</span>                                      <span class="token comment"># 当我们需要将其传递给其它操作时</span>                                      <span class="token comment"># 例如当我们使用PWM时，只要我们将所有内容</span>                                      <span class="token comment"># 保持为无符号的16位数字，就不需要担心映射命令之类的</span>                                      <span class="token comment"># 事情</span>    utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><h1 id="8-PWM-Control"><a href="#8-PWM-Control" class="headerlink" title="8.PWM Control"></a>8.PWM Control</h1><p>从电位器中读取值用作PWM信号的控制<br>把信号馈送到rgbled的红色部分</p><pre class="line-numbers language-python" data-language="python"><code class="language-python"><span class="token keyword">import</span> machine<span class="token keyword">import</span> utimeled_red <span class="token operator">=</span> machine<span class="token punctuation">.</span>PWM<span class="token punctuation">(</span>machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">)</span><span class="token punctuation">)</span>  <span class="token comment"># 定于led为PWM输出</span>potentiomemter <span class="token operator">=</span> machine<span class="token punctuation">.</span>ADC<span class="token punctuation">(</span><span class="token number">26</span><span class="token punctuation">)</span>    <span class="token comment"># 定义一个称为电位计的变量，并将其定义为模拟输入，然后使用库的ADC功能</span>led_red<span class="token punctuation">.</span>freq<span class="token punctuation">(</span><span class="token number">1000</span><span class="token punctuation">)</span>  <span class="token comment"># 工作频率为1000赫兹</span><span class="token keyword">while</span> <span class="token boolean">True</span><span class="token punctuation">:</span>    led_red<span class="token punctuation">.</span>duty_u16<span class="token punctuation">(</span>potentiomemter<span class="token punctuation">.</span>read_u16<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span>  <span class="token comment"># 占空比是一个无符号的16位整数</span>                                                 <span class="token comment"># 其值是从读取电位器中的无符号的16位整数中获得的</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><h1 id="9-OLED"><a href="#9-OLED" class="headerlink" title="9.OLED"></a>9.OLED</h1><ul><li>PICO内部I2c总线零号</li><li>两个I2C总线</li><li>只需要写入</li><li>只需3.3v</li></ul><p><img src="https://img-blog.csdnimg.cn/42e7372086f44ebca26fc36391a279cd.png" alt="![[Pasted image 20220921004505.png]]"></p><p>驱动显示器的脚本：</p><p>需要导入这个oled 的库</p><p>进入工具的包管理下载对应的包<br><img src="https://img-blog.csdnimg.cn/44e4ab2856124f779afc77c82db293cd.png" alt="![[Pasted image 20220921005140.png]]"></p><pre class="line-numbers language-python" data-language="python"><code class="language-python"><span class="token keyword">import</span> machine<span class="token keyword">import</span> utimesda <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">)</span>scl <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">21</span><span class="token punctuation">)</span>i2c <span class="token operator">=</span> machine<span class="token punctuation">.</span>I2C<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> sda <span class="token operator">=</span> sda<span class="token punctuation">,</span> scl <span class="token operator">=</span> scl<span class="token punctuation">,</span> freq <span class="token operator">=</span> <span class="token number">400000</span><span class="token punctuation">)</span> <span class="token comment"># 设置I2C对象，（使用哪个总线0还是1，赋值，i2c所在总线的频率  ）</span><span class="token comment"># 使用库</span><span class="token keyword">from</span> ssd1306 <span class="token keyword">import</span>  SSD1306_I2Coled <span class="token operator">=</span> SSD1306_I2C<span class="token punctuation">(</span><span class="token number">128</span><span class="token punctuation">,</span> <span class="token number">32</span><span class="token punctuation">,</span> i2c<span class="token punctuation">)</span>  <span class="token comment"># 不用给ssd1306分配i2c,因为这是一个固定的地址，内置在库中，不同的显示参数</span><span class="token comment"># 在屏幕上打印出文本</span>oled<span class="token punctuation">.</span>text<span class="token punctuation">(</span><span class="token string">'Welcome to the'</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span>oled<span class="token punctuation">.</span>text<span class="token punctuation">(</span><span class="token string">'Pi Pico'</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">10</span><span class="token punctuation">)</span>oled<span class="token punctuation">.</span>text<span class="token punctuation">(</span><span class="token string">'Display Demo'</span><span class="token punctuation">,</span> <span class="token number">0</span> <span class="token punctuation">,</span><span class="token number">20</span><span class="token punctuation">)</span>oled<span class="token punctuation">.</span>show<span class="token punctuation">(</span><span class="token punctuation">)</span>utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">4</span><span class="token punctuation">)</span>  oled<span class="token punctuation">.</span>fill<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>  <span class="token comment"># 填满显示屏</span>oled<span class="token punctuation">.</span>show<span class="token punctuation">(</span><span class="token punctuation">)</span>utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span>oled<span class="token punctuation">.</span>fill<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>   <span class="token comment"># 清空显示屏</span>oled<span class="token punctuation">.</span>show<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token comment"># 循环滚动</span><span class="token keyword">while</span> <span class="token boolean">True</span><span class="token punctuation">:</span>  oled<span class="token punctuation">.</span>text<span class="token punctuation">(</span><span class="token string">"Hello  World"</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span>  <span class="token keyword">for</span> i <span class="token keyword">in</span> <span class="token builtin">range</span> <span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span><span class="token number">164</span><span class="token punctuation">)</span><span class="token punctuation">:</span>  oled<span class="token punctuation">.</span>sroll<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span>    <span class="token comment">#滚动一次只移动一个像素</span>  oled<span class="token punctuation">.</span>show<span class="token punctuation">(</span><span class="token punctuation">)</span>  utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">0.01</span><span class="token punctuation">)</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><h1 id="10-H桥控制器小型直流电机"><a href="#10-H桥控制器小型直流电机" class="headerlink" title="10.H桥控制器小型直流电机"></a>10.H桥控制器小型直流电机</h1><p><img src="https://img-blog.csdnimg.cn/378a0b5675184150857f293f7af7ab99.png" alt="![[Pasted image 20220921011209.png]]"></p><ul><li>gpio上的PWM调制脉冲来控制直流电机的速度</li><li>使用MOSFET 的H桥驱动器</li></ul><p><img src="https://img-blog.csdnimg.cn/2554536940b54e2ba6b178ccb0ad2529.png" alt="![[Pasted image 20220921011512.png]]"></p><p>ADC电机 6v<br>tb 6612 fng 8桥电机驱动器  双批次桥， 但是只使用一面<br>6v 的电源</p><pre class="line-numbers language-python" data-language="python"><code class="language-python"><span class="token keyword">import</span> machine<span class="token keyword">import</span> utime<span class="token comment"># 设置电位计，作为模拟1到数字输入</span>potentiometer <span class="token operator">=</span> machine<span class="token punctuation">.</span>ADC<span class="token punctuation">(</span><span class="token number">26</span><span class="token punctuation">)</span><span class="token comment"># 设置H桥控制器引脚</span><span class="token comment"># AI1,2控制电机的旋转方向</span><span class="token comment"># PWMa控制马达的速度</span>mtr_AI1 <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">8</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>OUT<span class="token punctuation">)</span>mtr_AI2 <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">7</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>OUT<span class="token punctuation">)</span>mtr_PWMa <span class="token operator">=</span> machine<span class="token punctuation">.</span>PWM<span class="token punctuation">(</span>machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">6</span><span class="token punctuation">)</span><span class="token punctuation">)</span>button_red <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">15</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>IN<span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>PULL_DOWN<span class="token punctuation">)</span>  <span class="token comment"># 红色按钮下拉电阻</span>button_black <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>IN<span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>PULL_UP<span class="token punctuation">)</span>    <span class="token comment"># 黑色按钮上拉电阻</span>led_red <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>OUT<span class="token punctuation">)</span>led_green <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">11</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>OUT<span class="token punctuation">)</span>led_blue <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">14</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>OUT<span class="token punctuation">)</span>led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>mtr_PWMa<span class="token punctuation">.</span>freq<span class="token punctuation">(</span><span class="token number">50</span><span class="token punctuation">)</span>  <span class="token comment">#输入的PWM频率1设置为50赫兹，猜测</span>mtr_AI1<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>   <span class="token comment"># 让马达以特定的方向旋转</span>mtr_AI1<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token keyword">while</span> <span class="token boolean">True</span><span class="token punctuation">:</span><span class="token comment"># 当驱动LED时我们采用的是PWM的占空比，并将其与电位计的读数相匹配</span>      mtr_PWMa<span class="token punctuation">.</span>duty_u16<span class="token punctuation">(</span>potentiometer<span class="token punctuation">.</span>read_u16<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span>     <span class="token keyword">if</span> button_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">==</span> <span class="token number">1</span><span class="token punctuation">:</span>         mtr_AI1<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>         mtr_AI2<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>         led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>         led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>         led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>          <span class="token keyword">if</span> button_black<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">==</span> <span class="token number">0</span><span class="token punctuation">:</span>         mtr_AI1<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>         mtr_AI2<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>         led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>         led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>         led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">0.25</span><span class="token punctuation">)</span>   <span class="token comment"># 防反跳按钮</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><h1 id="11-用上全部"><a href="#11-用上全部" class="headerlink" title="11.用上全部"></a>11.用上全部</h1><pre class="line-numbers language-python" data-language="python"><code class="language-python"><span class="token keyword">import</span> machine<span class="token keyword">import</span> utime<span class="token comment"># 设置电位计，作为模拟1到数字输入</span>potentiometer <span class="token operator">=</span> machine<span class="token punctuation">.</span>ADC<span class="token punctuation">(</span><span class="token number">26</span><span class="token punctuation">)</span><span class="token comment"># 设置H桥控制器引脚</span><span class="token comment"># AI1,2控制电机的旋转方向</span><span class="token comment"># PWMa控制马达的速度</span>mtr_AI1 <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">8</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>OUT<span class="token punctuation">)</span>mtr_AI2 <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">7</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>OUT<span class="token punctuation">)</span>mtr_PWMa <span class="token operator">=</span> machine<span class="token punctuation">.</span>PWM<span class="token punctuation">(</span>machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">6</span><span class="token punctuation">)</span><span class="token punctuation">)</span>button_red <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">15</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>IN<span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>PULL_DOWN<span class="token punctuation">)</span>  <span class="token comment"># 红色按钮下拉电阻</span>button_black <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>IN<span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>PULL_UP<span class="token punctuation">)</span>    <span class="token comment"># 黑色按钮上拉电阻</span>led_red <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>OUT<span class="token punctuation">)</span>led_green <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">11</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>OUT<span class="token punctuation">)</span>led_blue <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">14</span><span class="token punctuation">,</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">.</span>OUT<span class="token punctuation">)</span>sda <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">)</span>scl <span class="token operator">=</span> machine<span class="token punctuation">.</span>Pin<span class="token punctuation">(</span><span class="token number">21</span><span class="token punctuation">)</span>i2c <span class="token operator">=</span> machine<span class="token punctuation">.</span>I2C<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> sda <span class="token operator">=</span> sda<span class="token punctuation">,</span> scl <span class="token operator">=</span> scl<span class="token punctuation">,</span> freq <span class="token operator">=</span> <span class="token number">400000</span><span class="token punctuation">)</span> <span class="token comment"># 设置I2C对象，（使用哪个总线0还是1，赋值，i2c所在总线的频率  ）</span><span class="token comment"># 使用库</span><span class="token keyword">from</span> ssd1306 <span class="token keyword">import</span>  SSD1306_I2Coled <span class="token operator">=</span> SSD1306_I2C<span class="token punctuation">(</span><span class="token number">128</span><span class="token punctuation">,</span> <span class="token number">32</span><span class="token punctuation">,</span> i2c<span class="token punctuation">)</span>  <span class="token comment"># 不用给ssd1306分配i2c,因为这是一个固定的地址，内置在库中，不同的显示参数</span>oled<span class="token punctuation">.</span>text<span class="token punctuation">(</span><span class="token string">'Pico Motor Test'</span><span class="token punctuation">,</span> <span class="token number">0</span> <span class="token punctuation">,</span><span class="token number">0</span><span class="token punctuation">)</span>oled<span class="token punctuation">.</span>show<span class="token punctuation">(</span><span class="token punctuation">)</span>utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span>  led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span>led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span>led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token comment"># 设置电机频率的值</span>mtr_PWMa<span class="token punctuation">.</span>freq<span class="token punctuation">(</span><span class="token number">50</span><span class="token punctuation">)</span>  <span class="token comment">#输入的PWM频率1设置为50赫兹，猜测</span>mtr_AI1<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>   <span class="token comment"># 让马达以特定的方向旋转</span>mtr_AI1<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token keyword">while</span> <span class="token boolean">True</span><span class="token punctuation">:</span><span class="token comment">#  500计算速度值，在oled上创建条形图</span>    speedvalue <span class="token operator">=</span> <span class="token builtin">int</span><span class="token punctuation">(</span>potentiometer<span class="token punctuation">.</span>read_u16<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token operator">/</span><span class="token number">500</span><span class="token punctuation">)</span><span class="token comment"># 当驱动LED时我们采用的是PWM的占空比，并将其与电位计的读数相匹配</span>      mtr_PWMa<span class="token punctuation">.</span>duty_u16<span class="token punctuation">(</span>potentiometer<span class="token punctuation">.</span>read_u16<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span>    <span class="token keyword">if</span> button_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">==</span> <span class="token number">1</span><span class="token punctuation">:</span>         mtr_AI1<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>         mtr_AI2<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>         led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>         led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>         led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>         <span class="token keyword">if</span> button_black<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">==</span> <span class="token number">0</span><span class="token punctuation">:</span>         mtr_AI1<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>         mtr_AI2<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>         led_red<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>         led_green<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>         led_blue<span class="token punctuation">.</span>value<span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span>    oled<span class="token punctuation">.</span>fill_rect<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">15</span><span class="token punctuation">,</span> speedvalue<span class="token punctuation">,</span> <span class="token number">25</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span>  <span class="token comment"># oled上创建一个矩形，1,15经常启动的位置，速度值，25用来确定长度</span> <span class="token comment"># 11展示出来1</span>oled<span class="token punctuation">.</span>show<span class="token punctuation">(</span><span class="token punctuation">)</span>oled<span class="token punctuation">.</span>fill_rect<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">15</span><span class="token punctuation">,</span> speedvalue<span class="token punctuation">,</span> <span class="token number">25</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span>  <span class="token comment"># </span>utime<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">0.25</span><span class="token punctuation">)</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><a href="https://www.bilibili.com/video/BV1tr4y1N7pv/?vd_source=ee1eea60088211b9fa51cf93a31423da">视频教程</a></p>]]></content>
    
    
      
      
    <summary type="html">&lt;p&gt;&lt;a href=&quot;https://pico.org.cn/&quot;&gt;树莓派 Pico 中文站&lt;/a&gt;&lt;/p&gt;
&lt;h1 id=&quot;1-板子介绍&quot;&gt;&lt;a href=&quot;#1-板子介绍&quot; class=&quot;headerlink&quot; title=&quot;1.板子介绍&quot;&gt;&lt;/a&gt;1.板子介绍&lt;/h1&gt;&lt;p</summary>
      
    
    
    
    <category term="树莓派" scheme="https://yyzqlqc.github.io/categories/%E6%A0%91%E8%8E%93%E6%B4%BE/"/>
    
    
  </entry>
  
  <entry>
    <title>保姆级Obsidian学习教程【超完整，小白必备】</title>
    <link href="https://yyzqlqc.github.io/post/27fb5d91.html"/>
    <id>https://yyzqlqc.github.io/post/27fb5d91.html</id>
    <published>2022-12-26T16:16:02.572Z</published>
    <updated>2022-12-26T16:16:02.576Z</updated>
    
    <content type="html"><![CDATA[<h1 id="前言"><a href="#前言" class="headerlink" title="前言"></a>前言</h1><ul><li>本篇文章学习视频来源：             <a href="https://www.bilibili.com/video/BV1MF411W7eD/?spm_id_from=333.788&amp;vd_source=ee1eea60088211b9fa51cf93a31423da">沙牛obsidian优质课程</a></li><li>学       习         软        件：                      <a href="https://obsidian.md/">obsidian</a></li><li>课   程   对   应   资    源：                      <a href="https://pan.sandox.top/s/O3pIW?path=/">云盘资源</a></li><li>说                                明：  Obsidian是基于<strong>Markdown文件</strong>的<strong>本地</strong>知识管理软件，并且开发者承诺Obsidian对于个人使用者<strong>永久免费</strong>。不同于云端笔记，ob在本地以文件夹的数据保存方式，更利于保存笔记，防止在云端的笔记丢失的情况，双链和丰富的插件功能能助使用者构建庞大的知识网络体系。</li></ul><hr><h1 id="学习网站："><a href="#学习网站：" class="headerlink" title="学习网站："></a>学习网站：</h1><blockquote><p><a href="https://github.com/Jackiexiao/obsidian">obsidian中文帮助手册</a></p></blockquote><blockquote><p><a href="https://help.obsidian.md/Advanced+topics/Community+plugins">官网帮助手册</a></p></blockquote><blockquote><p><a href="https://www.zybuluo.com/codeep/note/163962">Cmd Markdown 公式指导手册</a></p></blockquote><blockquote><p><a href="https://forum-zh.obsidian.md/">ob中文论坛</a></p></blockquote><hr><h1 id="笔记目录"><a href="#笔记目录" class="headerlink" title="笔记目录"></a>笔记目录</h1><ul><li><a href="https://blog.csdn.net/weixin_51684355/article/details/126064886?spm=1001.2014.3001.5502">Obsidian学习从0到1 —— 基本介绍</a></li><li><a href="https://editor.csdn.net/md/?articleId=126064933">Obsidian学习从0到1 —— MARKDOWN</a></li><li><a href="https://blog.csdn.net/weixin_51684355/article/details/126084867?spm=1001.2014.3001.5502">Obsidian学习从0到1 —— 双链（重点）</a></li><li><a href="https://editor.csdn.net/md/?articleId=126086160">Obsidian学习从0到1 —— 使用技巧</a></li><li><a href="https://blog.csdn.net/weixin_51684355/article/details/126089616?spm=1001.2014.3001.5502">Obsidian学习从0到1 —— 插件（上）</a></li><li><a href="https://blog.csdn.net/weixin_51684355/article/details/126089632?spm=1001.2014.3001.5502">Obsidian学习从0到1 —— 插件（下）</a></li><li><a href="https://blog.csdn.net/weixin_51684355/article/details/126091340?spm=1001.2014.3001.5502">Obsidian学习从0到1 —— 搜索和查询</a></li><li><a href="https://blog.csdn.net/weixin_51684355/article/details/126092705?spm=1001.2014.3001.5502">Obsidian学习从0到1 —— Dataview</a></li></ul><p>随视频课程持续更新……………<br>感谢支持</p>]]></content>
    
    
      
      
    <summary type="html">&lt;h1 id=&quot;前言&quot;&gt;&lt;a href=&quot;#前言&quot; class=&quot;headerlink&quot; title=&quot;前言&quot;&gt;&lt;/a&gt;前言&lt;/h1&gt;&lt;ul&gt;
&lt;li&gt;本篇文章学习视频来源：             &lt;a href=&quot;https://www.bilibili.com/video/</summary>
      
    
    
    
    <category term="Obsidian" scheme="https://yyzqlqc.github.io/categories/Obsidian/"/>
    
    
    <category term="工具教程" scheme="https://yyzqlqc.github.io/tags/%E5%B7%A5%E5%85%B7%E6%95%99%E7%A8%8B/"/>
    
  </entry>
  
  <entry>
    <title>C语言操作符【超全面归纳解析】</title>
    <link href="https://yyzqlqc.github.io/post/d66e415b.html"/>
    <id>https://yyzqlqc.github.io/post/d66e415b.html</id>
    <published>2022-12-25T16:56:29.035Z</published>
    <updated>2022-12-25T16:56:29.123Z</updated>
    
    <content type="html"><![CDATA[<h1 id="1-算数操作符"><a href="#1-算数操作符" class="headerlink" title="1.算数操作符"></a>1.算数操作符</h1><p><img src="https://img-blog.csdnimg.cn/36b1ae3e921c4b888e39d564c636df72.png"></p><pre class="line-numbers language-none"><code class="language-none">   +  - */%// 加 减 乘 除 取余<span aria-hidden="true" class="line-numbers-rows"><span></span><span></span></span></code></pre><blockquote><p>1.除了 % 操作符之外，其他的几个操作符可以作用于整数和浮点数<br>   2.对于 / 操作符如果两个操作数都为整数，执行整数除法（求商舍余）。而只要有浮点数，执行的就是浮点数除法。<br>   3.% (取模)操作符的两个操作数必须为整数，若其中一个不为整数则报错，返回的是整除之后的余数。</p></blockquote><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">5</span><span class="token punctuation">;</span><span class="token keyword">int</span> b <span class="token operator">=</span> <span class="token number">2</span><span class="token punctuation">;</span><span class="token keyword">int</span> c <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"a+b = %d\n"</span><span class="token punctuation">,</span> a <span class="token operator">+</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//相加</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"a-b = %d\n"</span><span class="token punctuation">,</span> a <span class="token operator">-</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//相减</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"a*b = %d\n"</span><span class="token punctuation">,</span> a <span class="token operator">*</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//相乘</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"a/b = %d\n"</span><span class="token punctuation">,</span> a <span class="token operator">/</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//求商</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"a%%b = %d\n"</span><span class="token punctuation">,</span> a <span class="token operator">%</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//取模</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/d864b2b7cb4144d98eb868a90297ddc3.png"></p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token comment">/*double a = 5.0 / 2;*/</span><span class="token keyword">double</span> a <span class="token operator">=</span> <span class="token number">5</span> <span class="token operator">%</span> <span class="token number">2.0</span><span class="token punctuation">;</span><span class="token comment">//报错</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"a = %lf"</span><span class="token punctuation">,</span> a<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><h1 id="2-移位操作符"><a href="#2-移位操作符" class="headerlink" title="2.移位操作符"></a>2.移位操作符</h1><p><img src="https://img-blog.csdnimg.cn/3fbc411b150e4001936cde6e9d77cfd4.png"></p><pre><code>&gt;&gt;    &lt;&lt;</code></pre><p>//右移      左移</p><blockquote><p>移位操作符可分为 算术移位 和 逻辑移位<br>算术移位： 先移位，然后补足符号位 (通常是这个)<br>逻辑移位： 直接移位，0补齐</p></blockquote><blockquote><p>总结：<br>1.左移移动一位正数相当于直接乘以2，负数也一样，移动n位，乘以2 ^ n。<br>2.左位移一位 *2，右位移一位 /2 （-1右位移还是-1）</p></blockquote><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string">&lt;stdio.h&gt;</span></span><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string">&lt;windows.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">16</span><span class="token punctuation">;</span><span class="token keyword">int</span> b <span class="token operator">=</span> a <span class="token operator">&lt;&lt;</span> <span class="token number">1</span><span class="token punctuation">;</span><span class="token keyword">int</span> c <span class="token operator">=</span> a <span class="token operator">&gt;&gt;</span> <span class="token number">2</span><span class="token punctuation">;</span><span class="token comment">//&gt;&gt;整数移位，移动的是二进制</span><span class="token comment">//0000 0000 0000 0000 0000 0000 0001 0000 </span><span class="token keyword">int</span> d <span class="token operator">=</span> <span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">;</span><span class="token keyword">int</span> e <span class="token operator">=</span> d <span class="token operator">&gt;&gt;</span> <span class="token number">1</span><span class="token punctuation">;</span><span class="token comment">//在计算机中，数据是用补码存储的</span><span class="token comment">//移位运算符操作的是补码</span><span class="token comment">//-1的补码：</span>    <span class="token comment">//1111 1111 1111 1111 1111 1111 1111 1111</span>    <span class="token comment">//移位后-1的二进制码不变</span>    <span class="token comment">//1111 1111 1111 1111 1111 1111 1111 1111 1</span>    <span class="token comment">//算数位移补符号位</span>    <span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//输出结果为32</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> c<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//输出结果为4</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> e<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//输出结果仍为-1，移位后-1的二进制码不变</span><span class="token function">system</span><span class="token punctuation">(</span><span class="token string">"Pause"</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/4bd9ab5f185b4fa5842dc465ca7014e1.png" alt="在这里插入图片描述"></p><blockquote><p>右移是以算术移位 的方式来进行右移的</p></blockquote><p>例如：<br><img src="https://img-blog.csdnimg.cn/c4cca5c2edee4d39a28160e0dd8707b7.png" alt="在这里插入图片描述"></p><p>我们先按照算术移位的方式去推导最终结果，然后再修改变量大小成 - 16进行验证。</p><p>警告：</p><blockquote><p>1.移位操作符只能作用于整数，不能用于浮点数，因为浮点数的存储方式跟整数完全不同<br>  2.对于移位运算符，不要移动负数位，这个是标准未定义的。<br>eg: int num = 10；<br>num &gt;&gt; -1;//error</p></blockquote><h1 id="3-位操作符"><a href="#3-位操作符" class="headerlink" title="3.位操作符"></a>3.位操作符</h1><table><thead><tr><th>C语言运算符表示</th><th>含义</th><th>示例</th></tr></thead><tbody><tr><td>&amp;</td><td>位与</td><td>x &amp; y</td></tr><tr><td></td><td></td><td>位或</td></tr><tr><td>^</td><td>异或</td><td>x ^ y</td></tr><tr><td>~</td><td>按位取反</td><td>x ~ y</td></tr></tbody></table><p>&amp; （按位与） 二进制补码 两真才真（1） 一假则假（0）<br>| （按位或） 二进制补码 一真则真（1） 两假才假（0）<br>^ (按位异或） 二进制补码 相异为真（1） 相同为假 (0）</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">3</span><span class="token punctuation">;</span>        <span class="token comment">//00000000 00000000 00000000 00000011</span><span class="token keyword">int</span> b <span class="token operator">=</span> <span class="token number">5</span><span class="token punctuation">;</span>        <span class="token comment">//00000000 00000000 00000000 00000101</span>    <span class="token keyword">int</span> c1 <span class="token operator">=</span> a <span class="token operator">&amp;</span> b<span class="token punctuation">;</span>   <span class="token comment">//00000000 00000000 00000000 00000001  =1</span><span class="token keyword">int</span> c2 <span class="token operator">=</span> a <span class="token operator">|</span> b<span class="token punctuation">;</span>   <span class="token comment">//00000000 00000000 00000000 00000111  =7</span><span class="token keyword">int</span> c3 <span class="token operator">=</span> a <span class="token operator">^</span> b<span class="token punctuation">;</span>   <span class="token comment">//00000000 00000000 00000000 00000110  =6</span>    <span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"c1 = %d\n"</span><span class="token punctuation">,</span> c1<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"c2 = %d\n"</span><span class="token punctuation">,</span> c2<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"c3 = %d\n"</span><span class="token punctuation">,</span> c3<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/9d956775963d47d3815f8c66e8a8d173.png" alt="在这里插入图片描述"></p><p><strong>练习1：不用临时变量，交换a，b的值</strong></p><blockquote><p>不用临时变量，交换a，b的值</p></blockquote><p>假设我们给定两个数，a = 3, b = 5;</p><p>要实现两个数的交换，我们会想到醋和酱油交换的生活案例，我们会先找一个空瓶子，先将醋或者酱油倒到空瓶子中，（假设将醋先倒入空瓶子中）然后我们会将酱油倒入原醋瓶中，将原空瓶中的醋倒入酱油瓶中。<br>方法①根据这种方式，我们会先创建一个临时变量来用于两者的数值交换</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">3</span><span class="token punctuation">;</span><span class="token keyword">int</span> b <span class="token operator">=</span> <span class="token number">5</span><span class="token punctuation">;</span><span class="token keyword">int</span> temp <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"before:a = %d,b = %d\n"</span><span class="token punctuation">,</span> a<span class="token punctuation">,</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span>temp <span class="token operator">=</span> a<span class="token punctuation">;</span>a <span class="token operator">=</span> b<span class="token punctuation">;</span>b <span class="token operator">=</span> temp<span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"after:a = %d,b = %d"</span><span class="token punctuation">,</span> a<span class="token punctuation">,</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p>但是我们题目中明确要求不能创建变量，所以这种方式明显不合适。</p><p>这时候我们考虑另外一种方式，②从数学的角度出发：如果我先将 a与b之和放到a到当中 然后再用两者之和减去b不就得到a了吗，并把这个值赋给b，实现了a的值转移给b 。同理，用两者之和减去刚刚赋予a值到b中的b，就能得到原b的值（听起来有点绕是不，简单来说：就是 值：a + b - a = b = &gt; 变量a</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token comment">//方法一：加减法</span><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token comment">//不创建临时变量实现两个数的交换</span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">3</span><span class="token punctuation">;</span><span class="token keyword">int</span> b <span class="token operator">=</span> <span class="token number">5</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"before:a = %d,b = %d\n"</span><span class="token punctuation">,</span> a<span class="token punctuation">,</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span>a <span class="token operator">=</span> a <span class="token operator">+</span> b<span class="token punctuation">;</span>b <span class="token operator">=</span> a <span class="token operator">-</span> b<span class="token punctuation">;</span><span class="token comment">//将a的值给b</span>a <span class="token operator">=</span> a <span class="token operator">-</span> b<span class="token punctuation">;</span><span class="token comment">//将b的值给a</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"after:a = %d,b = %d"</span><span class="token punctuation">,</span> a<span class="token punctuation">,</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/63e07a03c34c4c7c8d441e1ae9f10f61.png" alt="在这里插入图片描述"></p><p>虽然上面说的这种方式实现了不用创建临时变量就交换两个数值，但是仍然存在一定的缺陷，比如我们的变量a, b并不等于3和5，而是一个很大或者离int边界阈值很接近的值，如果我们用两者相加的方法，a + b很有可能就超出int类型的边界阈值，得到一个并非我们想要的结果，再拿着这个结果去减去a或者b中一个数，并不能得到原本的另一个数的正确值。也就是存在“可能溢出”的缺陷。</p><p>③既然这种加减法因为阈值的问题存在缺陷，我们就要去考虑一种既能够成功交换两个数的值，还不会存在阈值的缺陷，更深层次的思考，数值的存储方式– - 二进制，二进制能实现两者交换……a thousand years later—&gt;异或操作符 ^ 这种位操作符不会产生进位的情况，所以不存在溢出的可能。<img src="https://img-blog.csdnimg.cn/5307a9cf96a648d0afeb218a4ef889d3.png"></p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token comment">//异或办法</span><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token comment">//不创建临时变量实现两个数的交换</span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">3</span><span class="token punctuation">;</span><span class="token keyword">int</span> b <span class="token operator">=</span> <span class="token number">5</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"before:a = %d,b = %d\n"</span><span class="token punctuation">,</span> a<span class="token punctuation">,</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span>a <span class="token operator">=</span> a <span class="token operator">^</span> b<span class="token punctuation">;</span>b <span class="token operator">=</span> a <span class="token operator">^</span> b<span class="token punctuation">;</span>a <span class="token operator">=</span> a <span class="token operator">^</span> b<span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"after:a = %d,b = %d"</span><span class="token punctuation">,</span> a<span class="token punctuation">,</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/5307a9cf96a648d0afeb218a4ef889d3.png"></p><p><strong>练习2：求一个整数存储在内存中的二进制中1的个数</strong><br>编写代码实现：求一个整数存储在内存中的二进制中1的个数</p><p>方法①：看到这个问题，我们可以想到利用整数求其二进制原码，只要在求的过程中判断余数是否为1，是就计数 + 1，根据这种想法，编写我的代码可以得到：</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token keyword">int</span> count <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token function">scanf</span><span class="token punctuation">(</span><span class="token string">"%d"</span><span class="token punctuation">,</span> <span class="token operator">&amp;</span>a<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">while</span> <span class="token punctuation">(</span>a<span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token punctuation">(</span>a <span class="token operator">%</span> <span class="token number">2</span><span class="token punctuation">)</span> <span class="token operator">==</span> <span class="token number">1</span><span class="token punctuation">)</span>count<span class="token operator">++</span><span class="token punctuation">;</span>    a <span class="token operator">=</span> a <span class="token operator">/</span> <span class="token number">2</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"count = %d\n"</span><span class="token punctuation">,</span> count<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/21841e1477124f3fa47a09eee6e8a367.png" alt="在这里插入图片描述"></p><p>这种方式看似正确，但是当我们输入负数的时候，比如 - 1， - 1补码为11111111 11111111 11111111 11111111 正确答案应该为：32 ，而我们程序运行却得到0。<br>（实际上这种方式还有补救方法，只要将 负数看作无符号位的整型，将a定义从 int a = 0; 成更改成<strong>unsigned int a - 1就会被当作一个超级大的数字11111111 11111111 11111111 11111111 来处理）</strong><br><img src="https://img-blog.csdnimg.cn/96c29bd9c9a14fbd91b3459bd55ddbd7.png" alt="在这里插入图片描述"></p><p>方法②：既然这种方法不可行，我们就应该换一种思路，寻找新的方法，比如我能否得到输入数字存储的二进制补码，然后统计该补码中1的个数？答案是：可以，我们应该要想到任何一个数如果和 1进行按位与操作，若其最后一位数为1，则结果为1，若为0，结果为0。再借助移位操作符右移便可以统计1的个数（int类型的大小 为32位bit），因此可以编写代码为：</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token keyword">int</span> count <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token function">scanf</span><span class="token punctuation">(</span><span class="token string">"%d"</span><span class="token punctuation">,</span> <span class="token operator">&amp;</span>a<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">for</span> <span class="token punctuation">(</span>i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator">&lt;</span> <span class="token number">32</span><span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token number">1</span> <span class="token operator">==</span> <span class="token punctuation">(</span><span class="token punctuation">(</span>a <span class="token operator">&gt;&gt;</span> i<span class="token punctuation">)</span> <span class="token operator">&amp;</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">{</span>count<span class="token operator">++</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span class="token punctuation">}</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"count = %d\n"</span><span class="token punctuation">,</span> count<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p>这里我们的判断条件是：<br><strong>if(1 == ((a &gt;&gt; i) &amp; 1))</strong></p><p>也就是将上面的1进行左移操作，然后将两者进行按位与操作，再比较1左移操作的结果 与按位与之后的结果是否相等，若相等，代表该二进制位置 为 1</p><p>方法③：通过对输入数字的二进制操作，从最后一位1开始，每一步减少一个1</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token keyword">int</span> count <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token function">scanf</span><span class="token punctuation">(</span><span class="token string">"%d"</span><span class="token punctuation">,</span> <span class="token operator">&amp;</span>a<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">while</span> <span class="token punctuation">(</span>a<span class="token punctuation">)</span><span class="token punctuation">{</span>count<span class="token operator">++</span><span class="token punctuation">;</span>a <span class="token operator">&amp;=</span> a <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">;</span><span class="token comment">//a = a &amp; (a - 1);</span><span class="token punctuation">}</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"count = %d\n"</span><span class="token punctuation">,</span> count<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p>a - 1能够让a的最后一位变成0 这种奇妙的感觉就像是三体小说中描写的“高维世界像低维世界塌陷”<br>有这样的一个公式 n &amp; (n - 1)<br>假设n = 13 其后四位二进制补码为 1101</p><blockquote><p>1101 —- n<br>1100 —- n - 1<br>1100 —- n = n &amp; (n - 1)<br>1011 —- n - 1<br>1000 —- n = n &amp; (n - 1)<br>0111 —- n - 1<br>0000 —- n = n &amp; (n - 1)</p></blockquote><p>我们可以观察n的变化，发现每一次进行n = n &amp; (n - 1)后，其最后一位的1（最右边的1）都会变成0（每执行一次，最右边的1都会消失，直到变成0，停止执行），那么在n变成0之前，n = n &amp; (n - 1)能执行多少次，就代表最初的n中二进制补码就有多少个1。<br>这种算法的执行次数不用每次都执行32次，有多少个1，就执行多少次，所以效率很高！</p><blockquote><p>注意：位操作符在进行运算的时候，不需要考虑符号位的影响，所有位都当做需要参与运算的二进制位，<br>   比如 - 1 ^ -1 = 0, 即符号位也正常参与位操作符运算。</p></blockquote><p>4.复合赋值符</p><p><img src="https://img-blog.csdnimg.cn/829868b7c9d647c389e53f0cb6f1ea48.png" alt="在这里插入图片描述"></p><p>①<strong>简单赋值操作符：</strong></p><p>= 赋值操作符（注意：一个等号 = 表示赋值，两个等号 == 表示条件判断）<br>通过赋值操作符，我们可以给初始变量赋值，变更调整变量的值（也就是重新给变量赋值）<br>例如：</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token keyword">int</span> weight <span class="token operator">=</span> <span class="token number">80</span><span class="token punctuation">;</span><span class="token comment">//单位kg </span>weight <span class="token operator">=</span> <span class="token number">60</span><span class="token punctuation">;</span><span class="token comment">//对80不满意，重新赋值成60</span><span class="token keyword">double</span> salary <span class="token operator">=</span> <span class="token number">10000.0</span><span class="token punctuation">;</span>salary <span class="token operator">=</span> <span class="token number">30000.0</span><span class="token punctuation">;</span><span class="token comment">//对salary只有10000.0不满意，变成30000.0</span><span class="token comment">//赋值操作符也可以连续使用，比如</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">10</span><span class="token punctuation">;</span><span class="token keyword">int</span> x <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token keyword">int</span> y <span class="token operator">=</span> <span class="token number">20</span><span class="token punctuation">;</span>a <span class="token operator">=</span> x <span class="token operator">=</span> y <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">;</span> <span class="token comment">//连续赋值  //赋值操作符是从右往左计算的</span><span class="token comment">//等同于：</span>x <span class="token operator">=</span> y <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">;</span>a <span class="token operator">=</span> x<span class="token punctuation">;</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p>一般我们都是用分开的形式，不用连续赋值的形式，因为分开表示的方法更加容易阅读和理解，且易于调试。</p><p>②<strong>复杂赋值操作符</strong></p><p>+= 、-= 、 *= 、 /=、 %= 、 &gt;&gt;=、 &lt;&lt;=、 &amp;=、 |=、 ^=<br>举例：<br>int x = 10;<br>x = x + 10;<br>等同于：x += 10;</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> a <span class="token operator">+=</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> a <span class="token operator">-=</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> a <span class="token operator">*=</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> a <span class="token operator">/=</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> a <span class="token operator">%=</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> a <span class="token operator">&lt;&lt;=</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> a <span class="token operator">&gt;&gt;=</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> a <span class="token operator">&amp;=</span> <span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> a <span class="token operator">|=</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> a <span class="token operator">^=</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/8d10e27e39fa44d2af8af9c70bf09ad8.png" alt="在这里插入图片描述"></p><h1 id="4-单目操作符"><a href="#4-单目操作符" class="headerlink" title="4.单目操作符"></a>4.单目操作符</h1><p><img src="https://img-blog.csdnimg.cn/54e1e137e76e4dbfa8e570bcaf58e116.png" alt="在这里插入图片描述"></p><p><strong>sizeof 详细讲解：</strong></p><p>举例一：</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span><span class="token comment">//一个整形为4的字节</span><span class="token keyword">char</span> b <span class="token operator">=</span> <span class="token char">'A'</span><span class="token punctuation">;</span><span class="token keyword">int</span> arr<span class="token punctuation">[</span><span class="token number">20</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">{</span> <span class="token number">0</span> <span class="token punctuation">}</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> <span class="token keyword">sizeof</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> <span class="token keyword">sizeof</span> a<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> <span class="token keyword">sizeof</span><span class="token punctuation">(</span><span class="token keyword">int</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> <span class="token keyword">sizeof</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> <span class="token keyword">sizeof</span><span class="token punctuation">(</span><span class="token keyword">char</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> <span class="token keyword">sizeof</span><span class="token punctuation">(</span>arr<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> <span class="token keyword">sizeof</span><span class="token punctuation">(</span><span class="token keyword">int</span><span class="token punctuation">[</span><span class="token number">20</span><span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/44cb8cff7ecb4f7db9c394a6dec12cef.png" alt="在这里插入图片描述"></p><p>举例二：</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">short</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token keyword">int</span> j <span class="token operator">=</span> <span class="token number">10</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> <span class="token keyword">sizeof</span><span class="token punctuation">(</span>i <span class="token operator">=</span> j <span class="token operator">+</span> <span class="token number">5</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//sizeof计算所占空间的大小</span><span class="token comment">//不管这里的j是什么类型  j+5的结果都是放到变量 i当中  而i又是short类型</span><span class="token comment">//sizeof(i=j+5)等于 sizeof(i)等于sizeof(short)等于2</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> i<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//sizeof里面放的表达式并不会真实进行运算，只是一个摆设</span><span class="token comment">//也就是说 i=j+5 这一步操作并未真实执行，所以i还是原来的值：0</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/73b8c32856df4059a5606a73146460b8.png" alt="在这里插入图片描述"></p><blockquote><p>注意：sizeof括号中的表达式不参与实际运算！</p></blockquote><p>~ 按位取反详解：<br>按二进制补码取反<br>例如 0：00000000 00000000 00000000 00000000<br>~0：11111111 11111111 11111111 11111111 补码 等于 - 1</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> <span class="token operator">~</span>a<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/04f9f9272dd249769ad25c26ad21ee77.png" alt="在这里插入图片描述"></p><p>举例1：</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">11</span><span class="token punctuation">;</span><span class="token comment">//00000000 00000000 00000000 00001011 让倒数第三位变成1，其余不变</span><span class="token comment">//00000000 00000000 00000000 00000100  按位或  就能得到</span><span class="token comment">//1 &lt;&lt; 2 1左移2位得到 00000000 00000000 00000000 00000100</span><span class="token comment">//int j = i | 4;</span><span class="token keyword">int</span> j <span class="token operator">=</span> i <span class="token operator">|</span> <span class="token punctuation">(</span><span class="token number">1</span> <span class="token operator">&lt;&lt;</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> j<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//将j变成原来的i  只需要按位与操作</span><span class="token comment">//00000000 00000000 00000000 00001111</span><span class="token comment">//11111111 11111111 11111111 11111011</span><span class="token comment">//00000000 00000000 00000000 00001011</span><span class="token comment">//而  11111111 11111111 11111111 11111011 可以由按位取反得到</span><span class="token comment">//    00000000 00000000 00000000 00000100  这个数又可以通过1左移2位得到</span>j <span class="token operator">=</span> j <span class="token operator">&amp;</span> <span class="token punctuation">(</span><span class="token operator">~</span><span class="token punctuation">(</span><span class="token number">1</span> <span class="token operator">&lt;&lt;</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> j<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//int a = 0;</span><span class="token comment">//printf("%d\n", ~a);</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/4fc53ee7f23a44e2bf411326dcc2484f.png" alt="在这里插入图片描述"></p><p><strong>减减– 、 加加 ++ 详解：</strong></p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">10</span><span class="token punctuation">;</span><span class="token comment">//printf("%d\n", ++a);//前置++,先++，后打印</span><span class="token comment">//printf("%d\n", a++);//后置++,先打印，后++</span><span class="token comment">//printf("%d\n", --a);//前置--,先--，后打印</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> a<span class="token operator">--</span><span class="token punctuation">)</span><span class="token punctuation">;</span>后置<span class="token operator">--</span><span class="token punctuation">,</span>先打印，后<span class="token operator">--</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> a<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/65e0c40787b246b9a6a048059f54c06e.png" alt="在这里插入图片描述"></p><p><strong>(类型)强制类型转换详解：</strong></p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token keyword">int</span><span class="token punctuation">)</span><span class="token number">3.14</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> a<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/047f807e760743219f847c220965c5d0.png" alt="在这里插入图片描述"></p><p>练习：</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">void</span> <span class="token function">test1</span><span class="token punctuation">(</span><span class="token keyword">int</span> arr<span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> <span class="token keyword">sizeof</span><span class="token punctuation">(</span>arr<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span class="token keyword">void</span> <span class="token function">test2</span><span class="token punctuation">(</span><span class="token keyword">char</span> ch<span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> <span class="token keyword">sizeof</span><span class="token punctuation">(</span>ch<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> arr<span class="token punctuation">[</span><span class="token number">10</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">{</span> <span class="token number">0</span> <span class="token punctuation">}</span><span class="token punctuation">;</span><span class="token keyword">char</span> ch<span class="token punctuation">[</span><span class="token number">10</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">{</span> <span class="token number">0</span> <span class="token punctuation">}</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> <span class="token keyword">sizeof</span><span class="token punctuation">(</span>arr<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> <span class="token keyword">sizeof</span><span class="token punctuation">(</span>ch<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">test1</span><span class="token punctuation">(</span>arr<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">test2</span><span class="token punctuation">(</span>ch<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/f5b4a231c60742139f8ab1446beaf562.png" alt="在这里插入图片描述"></p><h1 id="5-关系操作符"><a href="#5-关系操作符" class="headerlink" title="5.关系操作符"></a>5.关系操作符</h1><p><img src="https://img-blog.csdnimg.cn/e0c508ce0eff450098d6e6b4857ba0f4.png" alt="在这里插入图片描述"></p><table><thead><tr><th>关系运算符释义</th><th>C语言表示</th><th>数学表示</th></tr></thead><tbody><tr><td>大于</td><td>&gt;</td><td>&gt;</td></tr><tr><td>大于等于</td><td>&gt;=</td><td>≥</td></tr><tr><td>等于</td><td>==</td><td>=</td></tr><tr><td>不等于</td><td>!=</td><td>≠</td></tr><tr><td>小于</td><td>&lt;</td><td>&lt;</td></tr><tr><td>小于等于</td><td>&lt;=</td><td>≤</td></tr></tbody></table><p><strong>关系运算符的应用</strong></p><ul><li>关系运算符的运算结果只有 0 或 1。当条件成立时结果为 1，条件不成立结果为 0。</li><li>我们来看一段代码，如下：<pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>    <span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> <span class="token number">1</span> <span class="token operator">&gt;</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span>    <span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> <span class="token number">1</span> <span class="token operator">&lt;</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span>    <span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre></li></ul><p>得到的输出结果为：</p><blockquote><p>0<br>  1</p></blockquote><blockquote><p>原因就是1 &gt; 2在数学上是不成立的，所以结果为0；而1 &lt; 2在数学上是不成立的，所以结果为1</p></blockquote><h1 id="6-逻辑操作符"><a href="#6-逻辑操作符" class="headerlink" title="6.逻辑操作符"></a>6.逻辑操作符</h1><blockquote><p>1.&amp;&amp; 逻辑与 判断规则：两真则真，一假就假<br>   2.|| 逻辑或 判断规则：一真则真，两假才假</p></blockquote><blockquote><p>详解：<br>位操作符中的 &amp; 和 | 操作的是数的二进制补码 逻辑操作符中的 &amp;&amp; 和 || 操作的是数本身 （数为0为假，数为非0为真）<br>使用逻辑操作符之后，若表达式整体判断为真，则值为1（1表示真，固定值） 若表达式整体判断为假，则值为0（0表示假，固定值）</p></blockquote><p>举例一：</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">,</span> a <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">,</span> b <span class="token operator">=</span> <span class="token number">2</span><span class="token punctuation">,</span> c <span class="token operator">=</span> <span class="token number">3</span><span class="token punctuation">,</span> d <span class="token operator">=</span> <span class="token number">4</span><span class="token punctuation">;</span>i <span class="token operator">=</span> a<span class="token operator">++</span> <span class="token operator">&amp;&amp;</span> <span class="token operator">++</span>b <span class="token operator">&amp;&amp;</span> d<span class="token operator">++</span><span class="token punctuation">;</span><span class="token comment">//a++ 先使用a的值0，再++, 判断a=0后，后面的 ++b &amp;&amp; d++均不执行</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"a = %d\nb = %d\nc = %d\nd = %d\n"</span><span class="token punctuation">,</span> a<span class="token punctuation">,</span> b<span class="token punctuation">,</span> c<span class="token punctuation">,</span> d<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/a2e2d687d84c46a19284909b4dc5233d.png" alt="在这里插入图片描述"></p><blockquote><p>总结:<br>逻辑与操作&amp;&amp; ： 左边判断为假后，右边的表达式不再执行，直接停止，返回值0（假）<br>逻辑或操作 || 左边判断为真后，右边的表达式不再执行，直接停止，返回值1（真）</p></blockquote><h1 id="7-条件操作符"><a href="#7-条件操作符" class="headerlink" title="7.条件操作符"></a>7.条件操作符</h1><blockquote><p>exp1 ? exp2 : exp3</p></blockquote><blockquote><p>解释：表达式1进行判断，若结果为真，则 exp1 ? exp2 : exp3 整体的结果为 表达式 exp2 的结果<br>   若结果为假，则exp1 ? exp2 : exp3 整体的结果为 表达式 exp3 的结果<br>   exp是expression的缩写，中文意思为“表达”</p></blockquote><p>举例：</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">10</span><span class="token punctuation">;</span><span class="token keyword">int</span> b <span class="token operator">=</span> <span class="token number">20</span><span class="token punctuation">;</span><span class="token keyword">int</span> max<span class="token punctuation">;</span><span class="token comment">//if (a &gt; 5)</span><span class="token comment">//b = 3;</span><span class="token comment">//else</span><span class="token comment">//b = -3;</span><span class="token comment">//b = a &gt; 5 ? 3 : -3;</span>max <span class="token operator">=</span> a <span class="token operator">&gt;</span> b <span class="token operator">?</span> a <span class="token operator">:</span> b<span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"a = %d\nb = %d\nmax = %d\n"</span><span class="token punctuation">,</span> a<span class="token punctuation">,</span> b<span class="token punctuation">,</span> max<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/f74847a5c16e4f7dabd546ed4567e677.png" alt="在这里插入图片描述"></p><h1 id="8-逗号表达式"><a href="#8-逗号表达式" class="headerlink" title="8.逗号表达式"></a>8.逗号表达式</h1><blockquote><p>exp1, exp2, exp3, …….expN</p></blockquote><blockquote><p>逗号表达式：就是用逗号隔开的多个表达式。<br>   逗号表达式，从左向右依次执行，整个表达式的结果是最后一个表达式的结果。</p></blockquote><p>举例1：</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span><span class="token keyword">int</span> b <span class="token operator">=</span> <span class="token number">2</span><span class="token punctuation">;</span><span class="token keyword">int</span> c <span class="token operator">=</span> <span class="token punctuation">(</span>a <span class="token operator">&gt;</span> b<span class="token punctuation">,</span> a <span class="token operator">=</span> b <span class="token operator">+</span> <span class="token number">10</span><span class="token punctuation">,</span> a<span class="token punctuation">,</span> b <span class="token operator">=</span> a <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> c<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p>讲解：这里我们要输出c的值，那么c的值是什么呢？</p><blockquote><p> int c = (a &gt; b, a = b + 10, a, b = a + 1);<br>这里初始化c的时候应用了逗号表达式，逗号表达式从左向右依次执行，整个表达式结果为最后一个表达式的结果，我们按照这个原则去推导，a &gt; b 执行但是没有结果 a = b + 10 相当于a = 2 + 10 = 12, a执行但不产生结果，b = a + 1 = 12 + 1 = 13，整个表达式的值也等于b 即c = 13。</p></blockquote><p>对于这个结果我们可以运行程序验证一下。</p><p><img src="https://img-blog.csdnimg.cn/922d30cd3c654837b51d34b916f89a9b.png" alt="在这里插入图片描述"></p><p>拓展：那这里a, b的值分别为多少呢？<br><img src="https://img-blog.csdnimg.cn/de183c07f96840c38fd5e0ea3e44e4fd.png" alt="在这里插入图片描述"></p><p>a = 12, b = 13 不再是原本的1和2，说明int c = (a &gt; b, a = b + 10, a, b = a + 1); 中运算的结果有效接保留了下来。</p><h1 id="9-下标引用、函数调用和结构成员"><a href="#9-下标引用、函数调用和结构成员" class="headerlink" title="9.下标引用、函数调用和结构成员"></a>9.下标引用、函数调用和结构成员</h1><p><strong>1.下标引用操作符 [ ]</strong><br>操作数： 一个数组名 + 一个索引值</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a<span class="token punctuation">[</span><span class="token number">10</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">{</span> <span class="token number">0</span> <span class="token punctuation">}</span><span class="token punctuation">;</span><span class="token comment">//1.定义一个数组</span><span class="token comment">//2.如果我们想要访问第5个数组元素，并给其赋值</span>a<span class="token punctuation">[</span><span class="token number">4</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token number">10</span><span class="token punctuation">;</span><span class="token comment">//3.用数组变量名+[]+下标索引数字</span><span class="token comment">//4.[ ] 对应的两个操作数一个是变量名a  另外一个就是下标/索引值 4</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> a<span class="token punctuation">[</span><span class="token number">4</span><span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/da9d9d277e784e978ab66bebb72fb505.png" alt="在这里插入图片描述"></p><p><strong>2.函数调用操作符()</strong><br>接收一个或者多个操作数，第一个操作数是函数名，剩余的操作数就是传递给函数的参数。</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token comment">//2.这个地方的()不是函数调用操作符，是函数定义的语法规则</span><span class="token keyword">int</span> <span class="token function">get_max</span><span class="token punctuation">(</span><span class="token keyword">int</span> x<span class="token punctuation">,</span> <span class="token keyword">int</span> y<span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">return</span> x <span class="token operator">&gt;</span> y <span class="token operator">?</span> x <span class="token operator">:</span> y<span class="token punctuation">;</span><span class="token punctuation">}</span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">10</span><span class="token punctuation">;</span><span class="token keyword">int</span> b <span class="token operator">=</span> <span class="token number">20</span><span class="token punctuation">;</span><span class="token comment">//1.调用函数的时候使用的() 就是函数调用操作符</span><span class="token keyword">int</span> max <span class="token operator">=</span> <span class="token function">get_max</span><span class="token punctuation">(</span>a<span class="token punctuation">,</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//3.这里的函数调用操作符()的操作数为 函数名get_max，函数参数a，函数参数b  总共三个操作数</span><span class="token comment">//4.对于函数调用操作符()而言，其操作数至少要有一个（函数名），可以有多个</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"max = %d\n"</span><span class="token punctuation">,</span> max<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/bf459f61d2254791a185c94a7764eff2.png" alt="在这里插入图片描述"></p><p><strong>3.访问一个结构的成员 . -&gt;</strong><br>思考：如何创建结构体类型和结构体类型变量呢？</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token comment">//1.现实中为了描述复杂的对象，构建结构体类型</span><span class="token comment">//2.比如学生，有姓名，年龄，学号等信息</span><span class="token comment">//创建一个结构体类型</span><span class="token keyword">struct</span> <span class="token class-name">Stu</span>  <span class="token comment">//3.struct Stu是一个结构体类型，表示学生类型</span><span class="token comment">//类型是用来创建变量的</span><span class="token punctuation">{</span><span class="token keyword">char</span> name<span class="token punctuation">[</span><span class="token number">20</span><span class="token punctuation">]</span><span class="token punctuation">;</span><span class="token comment">//姓名</span><span class="token keyword">int</span> age<span class="token punctuation">;</span><span class="token comment">//年龄</span><span class="token keyword">char</span> id<span class="token punctuation">[</span><span class="token number">20</span><span class="token punctuation">]</span><span class="token punctuation">;</span><span class="token comment">//学号</span><span class="token punctuation">}</span><span class="token punctuation">;</span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">10</span><span class="token punctuation">;</span><span class="token comment">//使用struct Stu这个类型创建了一个学生对象s1，并初始化</span><span class="token keyword">struct</span> <span class="token class-name">Stu</span> s1 <span class="token operator">=</span> <span class="token punctuation">{</span> <span class="token string">"张三"</span><span class="token punctuation">,</span><span class="token number">20</span><span class="token punctuation">,</span><span class="token string">"20210403"</span> <span class="token punctuation">}</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p>结构体类型和结构体类型变量详解：</p><blockquote><p>结构体类型和结构体类型变量的关系类似于图纸和房子的关系<br>在盖房子之前，需要有房屋盖建的设计图纸 。有了图纸，才能根据图纸盖出好房子。<br>在设计图纸环节，我们并不会真正去盖房子，所以就不会占用土地。<br>同样的道理，在创建结构体类型的时候，我们并不会真正去存储什么信息，只有在利用结构体类型创建变量的时候，才会去存储相应的信息，向内存申请存储空间。</p></blockquote><p>创建好结构体变量后，我们想要打印相关的信息来看一下，这时候就会用到访问一个结构的成员.或 -&gt;</p><p>1.结构体变量.成员名.操作符的操作数一个是结构体变量，另一个是成员名<br><img src="https://img-blog.csdnimg.cn/99b3f43f4bdd48a8a9b7214586111745.png" alt="在这里插入图片描述"></p><p>2.将结构的地址取出来放入指针，通过指针进行访问</p><p><img src="https://img-blog.csdnimg.cn/7a99b0f2cd2d4894a0b98d68accb86f1.png" alt="在这里插入图片描述"></p><p>第2中方式有点太啰嗦了，先要对指针解引用，如何通过.操作符访问结构体变量的成员。<br>实际上通过指针访问的方式可以更加精简一些</p><p>3.结构体指针-&gt;成员名 通过指针的方式直接访问到变量的成员。</p><p><img src="https://img-blog.csdnimg.cn/372c1d1d4a5f451da7b699753a8ec444.png" alt="在这里插入图片描述"></p><p>完整代码：</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token comment">//1.现实中为了描述复杂的对象，构建结构体类型</span><span class="token comment">//2.比如学生，有姓名，年龄，学号等信息</span><span class="token comment">//创建一个结构体类型</span><span class="token keyword">struct</span> <span class="token class-name">Stu</span>  <span class="token comment">//3.struct Stu是一个结构体类型，表示学生类型</span><span class="token comment">//类型是用来创建变量的</span><span class="token punctuation">{</span><span class="token keyword">char</span> name<span class="token punctuation">[</span><span class="token number">20</span><span class="token punctuation">]</span><span class="token punctuation">;</span><span class="token comment">//姓名</span><span class="token keyword">int</span> age<span class="token punctuation">;</span><span class="token comment">//年龄</span><span class="token keyword">char</span> id<span class="token punctuation">[</span><span class="token number">20</span><span class="token punctuation">]</span><span class="token punctuation">;</span><span class="token comment">//学号</span><span class="token punctuation">}</span><span class="token punctuation">;</span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> a <span class="token operator">=</span> <span class="token number">10</span><span class="token punctuation">;</span><span class="token comment">//使用struct Stu这个类型创建了一个学生对象s1，并初始化</span><span class="token keyword">struct</span> <span class="token class-name">Stu</span> s1 <span class="token operator">=</span> <span class="token punctuation">{</span> <span class="token string">"张三"</span><span class="token punctuation">,</span><span class="token number">20</span><span class="token punctuation">,</span><span class="token string">"20210403"</span> <span class="token punctuation">}</span><span class="token punctuation">;</span><span class="token keyword">struct</span> <span class="token class-name">Stu</span><span class="token operator">*</span> ps <span class="token operator">=</span> <span class="token operator">&amp;</span>s1<span class="token punctuation">;</span><span class="token comment">//结构体指针-&gt;成员名</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%s\n"</span><span class="token punctuation">,</span> ps<span class="token operator">-&gt;</span>name<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> ps<span class="token operator">-&gt;</span>age<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%s\n"</span><span class="token punctuation">,</span> ps<span class="token operator">-&gt;</span>id<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//printf("%s\n", (*ps).name);</span><span class="token comment">//printf("%d\n", (*ps).age);</span><span class="token comment">//printf("%s\n", (*ps).id);</span><span class="token comment">//printf("%s\n", s1.name);</span><span class="token comment">//printf("%d\n", s1.age);</span><span class="token comment">//printf("%s\n", s1.id);</span><span class="token comment">//结构体变量.成员名  .操作符的操作数一个是结构体变量，另一个是成员名</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/3b85b6e4ff604ba081754b578cea3f42.png" alt="在这里插入图片描述"></p><h1 id="10-表达式求值"><a href="#10-表达式求值" class="headerlink" title="10.表达式求值"></a>10.表达式求值</h1><p>表达式求值的顺序一部分是由操作符的优先级和结合性决定。<br>同样，有些表达式的操作数在求值的过程中可能需要转换为其他类型。</p><h1 id="11-隐式类型转换（悄悄的进行类型转换）"><a href="#11-隐式类型转换（悄悄的进行类型转换）" class="headerlink" title="11.隐式类型转换（悄悄的进行类型转换）"></a>11.隐式类型转换（悄悄的进行类型转换）</h1><p><strong>①C的整型算术运算总是至少以缺省整型类型的精度来进行的。</strong></p><p>为了获得这个精度，表达式中的字符和短整型操作数在使用之前被转换为普通整型，这种转换称为整型提升。<br>是不是看的不太懂？这里我们举例说明：</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">char</span> a <span class="token operator">=</span> <span class="token number">3</span><span class="token punctuation">;</span><span class="token comment">//00000000 00000000 00000000 00000011  整数3</span><span class="token comment">//00000011  -&gt;a   a是char类型，只有一个字节，这时候就会发生截断</span><span class="token comment">//截断的规则：挑最小最低位的字节内容</span><span class="token keyword">char</span> b <span class="token operator">=</span> <span class="token number">127</span><span class="token punctuation">;</span><span class="token comment">//00000000 00000000 00000000 01111111  整数127</span><span class="token comment">//01111111  -&gt;b</span><span class="token comment">//a+b  a和b如何相加 按照变量数据类型的符号位来提升的</span><span class="token comment">//00000011 -&gt;00000000 00000000 00000000 00000011</span><span class="token comment">//01111111 -&gt;00000000 00000000 00000000 01111111</span><span class="token comment">//           00000000 00000000 00000000 10000010</span><span class="token keyword">char</span> c <span class="token operator">=</span> a <span class="token operator">+</span> b<span class="token punctuation">;</span><span class="token comment">//这时候a，b被提升为普通整型</span><span class="token comment">//10000010 -&gt;c</span><span class="token comment">//后面我们要以%d的形式打印，需要进行整型提升：按照变量数据类型的符号位来提升的 </span><span class="token comment">//11111111 11111111 11111111 10000010  ---补码</span><span class="token comment">//11111111 11111111 11111111 10000001  ---反码</span><span class="token comment">//10000000 00000000 00000000 01111110  ---原码 -126</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> c<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%c\n"</span><span class="token punctuation">,</span> c<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/732f21a9a53f497ea6fe42887dc86d38.png" alt="在这里插入图片描述"></p><p>至于为什么% c打印出来的是 ? 需要我们后面进行思考。</p><blockquote><p>整型提升的意义∶<br>表达式的整型运算要在CPU的相应运算器件内执行，CPU内整型运算器(ALU)的操作数的字节长度一般就是int的字节长度，同时也是CPU的通用寄存器的长度。<br>因此，即使两个char类型的相加，在CPU执行时实际上也要先转换为CPU内整型操作数的标准长度。 通用CPU(general - purpose CPU)是难以直接实现两个8比特字节直接相加运算（虽然机器指令中可能有这种字节相加指令)。<br>所以，表达式中各种长度可能小于int长度的整型值，都必须先转换为int或unsigned int，然后才能送入CPU去执行运算。</p></blockquote><p>如何进行整型提升呢 ?<br>整型提升是按照变量的数据类型的符号位来提升的</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token comment">//负数的整型提升</span><span class="token keyword">char</span> c1 <span class="token operator">=</span> <span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">;</span>变量c1的二进制位<span class="token punctuation">(</span>补码<span class="token punctuation">)</span>中只有<span class="token number">8</span>个比特位<span class="token operator">:</span><span class="token number">1111111</span>因为<span class="token keyword">char</span>为有符号的<span class="token keyword">char</span>所以整型提升的时候，高位补充符号位，即为<span class="token number">1</span> 提升之后的结果是 <span class="token operator">:</span><span class="token number">11111111111111111111111111111111</span><span class="token comment">//正数的整型提升</span><span class="token keyword">char</span> c2 <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span>变量c2的二进制位<span class="token punctuation">(</span>补码<span class="token punctuation">)</span>中只有<span class="token number">8</span>个比特位<span class="token operator">:</span><span class="token number">00000001</span>因为<span class="token keyword">char</span> 为有符号的<span class="token keyword">char</span>所以整型提升的时候，高位补充符号位，即为<span class="token number">0</span> 提升之后的结果是 <span class="token operator">:</span><span class="token number">00000000000000000000000000000001</span><span class="token comment">//无符号整型提升，高位补0</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p>整型提升举例：<br><img src="https://img-blog.csdnimg.cn/e6b42a63b990400d83ecdf1a68a25384.png" alt="在这里插入图片描述"></p><blockquote><p>解析：<br>0xb6 b:10 / 1011 6 / 0110 b6 10110110 整型提升后 高位补符号位1 变成了<br>11111111 11111111 11111111 10110110<br>负数 0xb600 10110110 00000000<br>整型提升后 高位补符号位1<br>变成了 11111111 11111111 10110110 00000000 负数</p></blockquote><p>实例1中if语句里面进行了比较，比较也是一种运算，其中的a, b要进行整型提升, 但是c不需要整型提升a, b整型提升之后, 变成了负数, 所以表达式a == Oxb6, b == Oxb600的结果是假, 但是c不发生整型提升, 则表达式 c == Oxb6000000的结果是真, 所程序输出的结果是 : c</p><p><img src="https://img-blog.csdnimg.cn/5b4c4d8885d340a6b45a5f7f587ae674.png" alt="在这里插入图片描述"></p><p>解析：<br>实例2中的, c只要参与表达式运算, 就会发生整型提升<br>表达式 + c, 就会发生提升, 所以sizeof(+c)是4个字节.<br>表达式c，表达式(!c)中c实际参与了运算，会发生整型提升，在vs编译器中显示的这个结果实际上是有问题的，在Linux，gcc编译器下结果为4，实际结果也应该为4。</p><blockquote><p>总结：什么时候会参与整型提升？<br>总要字节长度小于int，参与到实际运算后就会进行整型提升。</p></blockquote><p>②<strong>算术转换</strong></p><p>如果某个操作符的各个操作数属于不同的类型，那么除非其中一个操作数的转换为另一个操作数的类型，否则操作就无法进行。下面的层次体系称为寻常算术转换。</p><blockquote><p>long doub1e<br>double<br>float<br>unsigned long int<br>long int<br>unsigned int<br>int</p></blockquote><p>如果某个操作数的类型在上面这个列表中排名较低，那么首先要转换为另外一个操作数的类型后执行运算。（比如说int类型跟float类型参与运算，先要将int转换为float类型，然后float类型与float类型运算)<br>int a = 1;<br>float b = 2.0<br>b = a + b;<br>(会先将a转换为float类型 a = 1.00000）</p><blockquote><p>警告 : 但是算术转换要合理，要不然会有一些潜在的问题。<br>例如：排名高的类型向低位转换的时候会出现精度丢失。<br>float f = 3.14;int num = f;//隐式转换，会有精度丢失</p></blockquote><p>③<strong>操作符的属性</strong></p><p>复杂表达式的求值有三个影响的因素。<br>1.操作符的优先级<br>2.操作符的结合性<br>3.是否控制求值顺序。<br>两个相邻的操作符先执行哪个 ? 取决于他们的优先级。如果两者的优先级相同，取决于他们的结合性。</p><p>**C语言操作符优先级、结合性参考表：<br><img src="https://img-blog.csdnimg.cn/eb8906bbd71549e88d6252dba4ac79b6.png" alt="在这里插入图片描述"></p><p>**常见问题解答：<br>1、如何记住运算符的15种优先级和结合性？<br>C语言中运算符种类比较繁多，优先级有15种，结合性有两种。<br>2、如何记忆两种结合性和15种优先级？下面讲述一种记忆方法。<br>结合性有两种，一种是自左至右，另一种是自右至左，大部分运算符的结合性是自左至右，只有单目运算符、三目运算符的赋值运算符的结合性自右至左。<br>优先级有15种。</p><p><strong>记忆方法：</strong></p><p><strong>记住一个最高的：构造类型的元素或成员以及小括号。</strong><br>记住一个最低的：逗号运算符。<br>剩余的是一、二、三、赋值。<br>意思是单目、双目、三目和赋值运算符。</p><p>在诸多运算符中，又分为：<br>算术、关系、逻辑。<br>两种位操作运算符中，移位运算符在算术运算符后边，逻辑位运算符在逻辑运算符的前面。再细分如下：<br>算术运算符分 * ， / ， % 高于 + ， - 。<br>关系运算符中，〉，〉 = ， &lt; ， &lt;= 高于 == ，！ = 。<br>逻辑运算符中，除了逻辑求反（！）是单目外，逻辑与（ &amp;&amp; ）高于逻辑或（ || ）。<br>逻辑位运算符中，除了逻辑按位求反（~）外，按位与（&amp;)高于按位半加（^)，高于按位或（ | ）。<br>这样就将15种优先级都记住了，再将记忆方法总结如下：<br>去掉一个最高的，去掉一个最低的，剩下的是一、二、三、赋值。双目运算符中，顺序为算术、关系和逻辑，移位和逻辑位插入其中。</p><h1 id="12-问题表达式"><a href="#12-问题表达式" class="headerlink" title="12.问题表达式"></a>12.问题表达式</h1><p>下面我们来看一些问题表达式：</p><p>//表达式的求值部分由操作符的优先级决定。</p><p><strong>表达式1</strong></p><blockquote><p>a * b + c * d + e * f;</p></blockquote><ol><li>注释∶代码1在计算的时候，由于比 + 的优先级高，只能保证，的计算是比 + 早，但是优先级并不能决定第三个 * 比第一个 + 早执行。<br>所以表达式的计算机顺序就可能是︰<br>a * bc * d<br>a * b + c * de * f<br>a * b + c * d + e * f<br>或者 :<br>a * bc * de * f<br>a * b + c * d<br>a * b + c * d + e * f</li></ol><p><strong>表达式2</strong></p><blockquote><p>c + –c;</p></blockquote><p>注释︰同上，操作符的优先级只能决定自减–的运算在 + 的运算的前面，但是我们并没有办法得知， + 操作符的左操作数的获取在右操作数之前还是之后求值，所以结果是不可预测的，是有歧义的。</p><p><strong>代码3</strong><br>非法表达式</p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">10</span><span class="token punctuation">;</span>i <span class="token operator">=</span> i<span class="token operator">--</span> <span class="token operator">-</span> <span class="token operator">--</span>i <span class="token operator">*</span> <span class="token punctuation">(</span>i <span class="token operator">=</span> <span class="token operator">-</span><span class="token number">3</span><span class="token punctuation">)</span> <span class="token operator">*</span> i<span class="token operator">++</span> <span class="token operator">+</span> <span class="token operator">++</span>i<span class="token punctuation">;</span> <span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"i = %d\n"</span>，i<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span><span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p>表达式3在不同编译器中测试结果不同，例如：</p><p><img src="https://img-blog.csdnimg.cn/4a948125e344410d9e85e5b07908b349.png" alt="在这里插入图片描述"></p><p><strong>代码4</strong></p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span><span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">fun</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>   <span class="token keyword">static</span> <span class="token keyword">int</span> count <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span>   <span class="token keyword">return</span> <span class="token operator">++</span>count<span class="token punctuation">;</span><span class="token punctuation">}</span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>   <span class="token keyword">int</span> answer<span class="token punctuation">;</span>   answer <span class="token operator">=</span> <span class="token function">fun</span><span class="token punctuation">(</span><span class="token operator">-</span><span class="token function">fun</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">*</span> <span class="token function">fun</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>   <span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span>answer<span class="token punctuation">)</span><span class="token punctuation">;</span><span class="token comment">//输出多少?</span>   <span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span>  <span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p><img src="https://img-blog.csdnimg.cn/c14bbc1750dd407dac2258a2af718606.png" alt="在这里插入图片描述"></p><p>这个代码有没有实际的问题 ?<br>有问题!<br>虽然在大多数的编译器上求得结果都是相同的。<br>但是上述代码answer = fun() - fun() * fun(); 中我们只能通过操作符的优先级得知︰先算乘法，再算减法。函数的调用先后顺序无法通过操作符的优先级确定。</p><p><strong>代码5</strong></p><pre class="line-numbers language-c" data-language="c"><code class="language-c"><span class="token macro property"><span class="token directive-hash">#</span><span class="token directive keyword">include</span> <span class="token string">&lt;stdio.h&gt;</span></span><span class="token keyword">int</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>     <span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span>     <span class="token keyword">int</span> ret <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token operator">++</span>i<span class="token punctuation">)</span> <span class="token operator">+</span><span class="token punctuation">(</span><span class="token operator">++</span>i<span class="token punctuation">)</span> <span class="token operator">+</span><span class="token punctuation">(</span><span class="token operator">++</span>i<span class="token punctuation">)</span><span class="token punctuation">;</span>     <span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span> ret<span class="token punctuation">)</span><span class="token punctuation">;</span>     <span class="token function">printf</span><span class="token punctuation">(</span><span class="token string">"%d\n"</span><span class="token punctuation">,</span>i<span class="token punctuation">)</span><span class="token punctuation">;</span>     <span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span> <span class="token punctuation">}</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre><p>尝试在Linux环境gcc编译器，vS2019环境下都执行，看结果。<br>Linux运行结果：10 4<br>VS2019运行结果：12 4</p><p>看看同样的代码产生了不同的结果，这是为什么 ?<br>简单看一下汇编代码.就可以分析清楚.<br>这段代码中的第一个 + 在执行的时候，**第三个是否执行，这个是不确定的，因为依靠操作符的优先级和结合性是无法决定第一个＋和第三个前置的先后顺序。</p><blockquote><p>总结∶我们写出的表达式如果不能通过操作符的属性确定唯一的计算路径，那这个表达式就是存在问题的。</p></blockquote><p><a href="https://blog.51cto.com/panyujie/3251460">详细文本</a></p>]]></content>
    
    
      
      
    <summary type="html">&lt;h1 id=&quot;1-算数操作符&quot;&gt;&lt;a href=&quot;#1-算数操作符&quot; class=&quot;headerlink&quot; title=&quot;1.算数操作符&quot;&gt;&lt;/a&gt;1.算数操作符&lt;/h1&gt;&lt;p&gt;&lt;img src=&quot;https://img-blog.csdnimg.cn/36b1ae3e921c</summary>
      
    
    
    
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    <published>2022-12-25T14:13:40.662Z</published>
    <updated>2022-12-25T14:13:40.666Z</updated>
    
    <content type="html"><![CDATA[<p>Welcome to <a href="https://hexo.io/">Hexo</a>! This is your very first post. Check <a href="https://hexo.io/docs/">documentation</a> for more info. If you get any problems when using Hexo, you can find the answer in <a href="https://hexo.io/docs/troubleshooting.html">troubleshooting</a> or you can ask me on <a href="https://github.com/hexojs/hexo/issues">GitHub</a>.</p><h2 id="Quick-Start"><a href="#Quick-Start" class="headerlink" title="Quick Start"></a>Quick Start</h2><h3 id="Create-a-new-post"><a href="#Create-a-new-post" class="headerlink" title="Create a new post"></a>Create a new post</h3><pre class="line-numbers language-bash" data-language="bash"><code class="language-bash">$ hexo new <span class="token string">"My New Post"</span><span aria-hidden="true" class="line-numbers-rows"><span></span></span></code></pre><p>More info: <a href="https://hexo.io/docs/writing.html">Writing</a></p><h3 id="Run-server"><a href="#Run-server" class="headerlink" title="Run server"></a>Run server</h3><pre class="line-numbers language-bash" data-language="bash"><code class="language-bash">$ hexo server<span aria-hidden="true" class="line-numbers-rows"><span></span></span></code></pre><p>More info: <a href="https://hexo.io/docs/server.html">Server</a></p><h3 id="Generate-static-files"><a href="#Generate-static-files" class="headerlink" title="Generate static files"></a>Generate static files</h3><pre class="line-numbers language-bash" data-language="bash"><code class="language-bash">$ hexo generate<span aria-hidden="true" class="line-numbers-rows"><span></span></span></code></pre><p>More info: <a href="https://hexo.io/docs/generating.html">Generating</a></p><h3 id="Deploy-to-remote-sites"><a href="#Deploy-to-remote-sites" class="headerlink" title="Deploy to remote sites"></a>Deploy to remote sites</h3><pre class="line-numbers language-bash" data-language="bash"><code class="language-bash">$ hexo deploy<span aria-hidden="true" class="line-numbers-rows"><span></span></span></code></pre><p>More info: <a href="https://hexo.io/docs/one-command-deployment.html">Deployment</a></p>]]></content>
    
    
      
      
    <summary type="html">&lt;p&gt;Welcome to &lt;a href=&quot;https://hexo.io/&quot;&gt;Hexo&lt;/a&gt;! This is your very first post. Check &lt;a href=&quot;https://hexo.io/docs/&quot;&gt;documentation&lt;/a&gt; for</summary>
      
    
    
    
    <category term="hexo" scheme="https://yyzqlqc.github.io/categories/hexo/"/>
    
    
    <category term="hexo" scheme="https://yyzqlqc.github.io/tags/hexo/"/>
    
    <category term="others" scheme="https://yyzqlqc.github.io/tags/others/"/>
    
  </entry>
  
  <entry>
    <title>阆苑学子linux大作业视频讲解</title>
    <link href="https://yyzqlqc.github.io/post/f1eb297c.html"/>
    <id>https://yyzqlqc.github.io/post/f1eb297c.html</id>
    <published>2022-12-25T14:07:49.180Z</published>
    <updated>2022-12-25T14:07:49.180Z</updated>
    
    <content type="html"><![CDATA[<div style="position: relative; width: 100%; height: 0; padding-bottom: 75%;">    <iframe src="//player.bilibili.com/player.html?aid=691516604&amp;bvid=BV1L24y1Q7qi&amp;cid=933444560&amp;page=1" scrolling="no" border="0" frameborder="no" framespacing="0" allowfullscreen="true" style="position:absolute; height: 100%; width: 100%;"> </iframe></div>]]></content>
    
    
      
      
    <summary type="html">&lt;div style=&quot;position: relative; width: 100%; height: 0; padding-bottom: 75%;&quot;&gt;
    &lt;iframe src=&quot;//player.bilibili.com/player.html?aid=691516</summary>
      
    
    
    
    <category term="大学" scheme="https://yyzqlqc.github.io/categories/%E5%A4%A7%E5%AD%A6/"/>
    
    
    <category term="大作业" scheme="https://yyzqlqc.github.io/tags/%E5%A4%A7%E4%BD%9C%E4%B8%9A/"/>
    
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