[316] - Did you know about std::rank/std::rank_v type_trait to get …

…the rank of the array?

README.md

@@ -12,7 +12,8 @@
 
 ### Tips
 
-* [[315]](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/blob/master/tips/315.md) - Did you about C++20 `is_layout_compatible_v` type_traits?
+* [[316]](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/blob/master/tips/316.md) - Did you know about `std::rank/std::rank_v` type_trait to get the rank of the array?
+* [[315]](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/blob/master/tips/315.md) - Did you know about C++20 `is_layout_compatible_v` type_traits?
 * [[314]](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/blob/master/tips/314.md) - Did you know that with gnu:C++26 a more parts of static reflection can be emulated?
 * [[313]](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/blob/master/tips/313.md) - Did you know that C++26 added #embed?
 * [[312]](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/blob/master/tips/312.md) - Did you know that C++20 added support for Unevaluated asm-declaration in constexpr functions?
@@ -24,9 +25,9 @@
 * [[306]](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/blob/master/tips/306.md) - Did you know about if/else hell anti-pattern?
 * [[305]](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/blob/master/tips/305.md) - Did you know about (rejected) proposal for homogeneous variadic function parameters?
 * [[304]](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/blob/master/tips/304.md) - Did you know that tuple can be implement just with lambdas?
-* [[303]](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/blob/master/tips/303.md) - Did you about typename erasure technique to reduce compilation times with templates?
-* [[302]](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/blob/master/tips/302.md) - Did you now that with concepts you can override a type?
-* [[301]](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/blob/master/tips/301.md) - Did you now that functions in <charconv> are constexpr since C++23?
+* [[303]](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/blob/master/tips/303.md) - Did you know about typename erasure technique to reduce compilation times with templates?
+* [[302]](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/blob/master/tips/302.md) - Did you know that with concepts you can override a type?
+* [[301]](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/blob/master/tips/301.md) - Did you know that functions in <charconv> are constexpr since C++23?
 * [[300]](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/blob/master/tips/300.md) - Did you know that C++23 added support for constexpr std::bitset?
 * [[299]](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/blob/master/tips/299.md) - Did you know that C++20 concepts can be used to avoid implicit conversions?
 * [[298]](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/blob/master/tips/298.md) - Did you know that C++23 added static operator()?

tips/315.md

@@ -1,6 +1,6 @@
 <details open><summary>Info</summary><p>
 
-* **Did you about C++20 `is_layout_compatible_v` type_trait?**
+* **Did you know about C++20 `is_layout_compatible_v` type_trait?**
 
   * https://eel.is/c++draft/meta.type.synop
 
@@ -58,10 +58,25 @@ static_assert(4 == count_compatible<int, int, const int, int const, unsigned con
 > https://godbolt.org/z/7cjqdxGxE
 
 </p></details><details><summary>Solutions</summary><p>
- 
+
  ```cpp
 template<class T, class... Ts>
 constexpr auto count_compatible = (std::is_layout_compatible_v<T, Ts> + ... + std::size_t{});
 ```
 > https://godbolt.org/z/8v741635E
 
+```cpp
+template<class T, class... Ts>
+constexpr auto count_compatible = []{
+    return (std::is_layout_compatible_v<T, Ts> + ...);
+}();
+```
+
+> https://godbolt.org/z/GEcr44h49
+
+```cpp
+template<class T, class... Ts>
+constexpr auto count_compatible = (... + std::is_layout_compatible_v<T, Ts>);
+```
+
+> https://godbolt.org/z/fxqYeben5

tips/316.md

@@ -0,0 +1,41 @@
+<details open><summary>Info</summary><p>
+
+* Did you know about `std::rank/std::rank_v` type_trait to get the rank of the array?
+
+  * https://eel.is/c++draft/meta.unary.prop.query#lib:rank
+
+</p></details><details open><summary>Example</summary><p>
+
+```cpp
+static_assert(0 == std::rank_v<void>);
+static_assert(0 == std::rank_v<int>);
+static_assert(1 == std::rank_v<int[]>);
+static_assert(0 == std::rank_v<int[0]>);
+static_assert(1 == std::rank_v<int[1]>);
+static_assert(1 == std::rank_v<int[42]>);
+static_assert(2 == std::rank_v<int[][2]>);
+static_assert(2 == std::rank_v<int[1][2]>);
+static_assert(3 == std::rank_v<int[1][2][3]>);
+```
+
+> https://godbolt.org/z/e657s3
+
+</p></details><details open><summary>Puzzle</summary><p>
+
+> Can you implement standard compliant version of `std::rank_v`?
+
+```cpp
+static_assert(0 == rank_v<void>);
+static_assert(0 == rank_v<int>);
+static_assert(1 == rank_v<int[]>);
+static_assert(0 == rank_v<int[0]>);
+static_assert(1 == rank_v<int[1]>);
+static_assert(1 == rank_v<int[42]>);
+static_assert(2 == rank_v<int[][2]>);
+static_assert(2 == rank_v<int[1][2]>);
+static_assert(3 == rank_v<int[1][2][3]>);
+```
+
+> https://godbolt.org/z/7Ms3W4TdP
+
+</p></details><details><summary>Solutions</summary><p>