How to replace a symbol in C++ using the #define directive?

Question

C++ / C#

I'm experimenting. If I understand correctly, #define creates a macro that allows you to substitute something anywhere in the code.
Is it possible to insert a sign into a statement with a comment?
The task is to do algebraic operations without branching.

#include <iostream>
#define Symbol symbol

int main()
{
  char symbol;
  double x, y;
  std::cin >>symbol >> x >> y;
  std::cout <<x Symbol y; //Сюда
}

Answer 1

If you want to implement a calculator like
double res = x OPERATOR y;
AND somehow substitute the desired operation in place of OPERATOR during program execution, then no, this is not possible in C++. Write 4 if-else branches for your calculator.

Answer 2

In other words. Everything that starts with # is a compiler directive and will be processed during compilation. In your case, there is an attempt to construct code at a stage when the code itself has already been built and is executable. In any case, you need to validate on input and discard the "hat" from the user)