#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;
}