go read file to string
#include <iostream>
#include <fstream>
#include <string>
int main() {
std::ifstream file("example.txt");
std::string file_content((std::istreambuf_iterator<char>(file)),
(std::istreambuf_iterator<char>()));
file.close();
std::cout << file_content << std::endl;
return 0;
}