#include <iostream>
#include <regex>
 
template <typename T, T& var>
std::string get_variable_name() {
  std::string str(__PRETTY_FUNCTION__);
  std::smatch match;
  std::regex pattern("T& var = ([^;]+)");
  std::regex_search(str, match, pattern);
  return match[1];
}
 
int main()
{
   extern char char_1;
   extern int int_2;
   extern double double_3;
   extern float float_4;
   extern std::string string_5;
 
   std::cout << get_variable_name<decltype(char_1), char_1>() << std::endl;
   std::cout << get_variable_name<decltype(int_2), int_2>() << std::endl;
   std::cout << get_variable_name<decltype(double_3), double_3>() << std::endl;
   std::cout << get_variable_name<decltype(float_4), float_4>() << std::endl;
   std::cout << get_variable_name<decltype(string_5), string_5>() << std::endl;
}
 

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