We will start with a file called VERSION, containing the following:

2.0.1-rc-2

This time, we will choose to go for more type safety, and will define PROGRAM_VERSION as a string constant in version.hpp.in:

#pragma once
  
#include <string>

const std::string PROGRAM_VERSION = "@PROGRAM_VERSION@";

We will include the generated version.hpp in the following example source code (example.cpp):

// provides PROGRAM_VERSION
#include "version.hpp"

#include <iostream>

int main() {
  std::cout << "This is output from code v" << PROGRAM_VERSION
                                            << std::endl;

  std::cout << "Hello CMake world!" << std::endl;
}