копирование - C++

#include <iostream>
#include <fstream>
#include <string>
#include <iterator>
 
void cp(std::ifstream &f, std::ofstream &t){
  std::string s( (std::istreambuf_iterator<char>(f)),
                  std::istreambuf_iterator<char>() );
  t << s;
}
 
int main(){
  std::ifstream ifs("1.txt");//From
  std::ofstream ofs("2.txt");//To
  if(!ifs || !ofs){
    std::cerr << "ERROR";
    return 1;
  }
  cp(ifs, ofs);
  return 0;
}