#include <iostream>

#define DEBUG_VAR(T) std::cout<<(#T)<<" = " <<(T)\          
                              <<" in "<<__FUNCTION__\       
                              <<"(...) on line "<<__LINE__\ 
                              <<" of "<<__FILE__<<std::endl;

int x = 4;

void foo()
{
  DEBUG_VAR(x);
  x = 5;
}

int main(int,char**)
{
  foo();
  DEBUG_VAR(x);

  return 0;
}