C++ - Simple Math Interpreter

I made this for fun, so there may or may not be some bad practice or anything like that! If there is an issue, I'm willing to fix it, but I do not have a lot of knowledge with C++.

An interpreter, written in C++, that can evaluate simple math calculations.

Credits

Credits to CodePulse for the Simple Math interpreter written in Python and credits to CoolDeveloper101 for his Simple Math Interpreter written in C#.

Here is CodePulse's simple math interpreter. Here is CoolDeveloper101's simple math interpreter and this.

Running the program

If you are using G++ (GNU Compiler Collection), there is a g++_compile.txt, so you can compile the interpreter into exe file.