c++ stream string into fiel

string filetostring(){
	ifstream file("file", ios::binary);
    string fileStr;

    istreambuf_iterator<char> inputIt(file), emptyInputIt;
    back_insert_iterator<string> stringInsert(fileStr);

    copy(inputIt, emptyInputIt, stringInsert);

    return fileStr;
}

#include <fstream>
#include <string>
#include <iostream>

int main()
{
    std::string input;
    std::cin >> input;
    std::ofstream out("output.txt");
    out << input;
    out.close();
    return 0;
}