#include <iostream>

#include <fstream>

 

int main()

{

    std::fstream out("test.txt", std::ios::out | std::ios::trunc | std::ios::binary);

    out << "hello world";

    out.flush();

 

    std::fstream in("test.txt", std::ios::in | std::ios::binary);

    std::cout << in.rdbuf();

    return 0;

}