Metafactorial

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

/*
this c++ program will create another c++ program with "metafactorial.cpp" name
which is going to compute factorial of some number n and display it
*/

std::string buildMetafactorial(int factorial)
{
    if (factorial == 0 || factorial == 1)
        return "metafactorial = 1;";
    else
    {
        std::string s = "metafactorial = ";
        for (int i = 1; i <= factorial; i++)
        {
            if (i == factorial)
            {
                s += std::to_string(i) + ";";
                break;
            }
            s += std::to_string(i) + " * ";
        }
        return s;
    }
}

int main()
{
    int factorial = 0;
    std::cin >> factorial;

    if (factorial >= 0)
    {
        std::fstream file("metafactorial.cpp", std::ios::out);

        file << "#include <iostream>" << std::endl << std::endl;
        file << "int main()" << std::endl;
        file << "{" << std::endl;

        file << "\t" << "int metafactorial = 0;" << std::endl;
        file << "\t" << buildMetafactorial(factorial) << std::endl;
        file << "\t" << "std::cout << metafactorial << std::endl;" << std::endl;

        file << "}" << std::endl;

        file.close();
        std::cout << "Metafactorial generated!" << std::endl;
        return 0;
    }

    std::cout << "Metafactorial wasn't generated!" << std::endl;
    return 1;
}