How to make copies of the executable itself in C++?

I want to make copies of an executable file itself multiple times.

I tried the following code:

#include <fstream>
#include <string>

int main() {
    std::ifstream from("main.exe", std::ios::binary);
    auto buf { from.rdbuf() };

    for(int x { 0 }; x <= 10; ++x) {
        std::string name { "main" + std::to_string(x) + ".exe" };

        std::ofstream out(name, std::ios::binary);
        out << buf;
        out.close();
    }

    from.close();
    return 0;
}

But it doesn't work as I expected (It does not copy the executable repeatedly. See the size column in the following screenshot):

How do I solve this problem?

Reading from the input file stream buffer consumes the data. You need to reset the stream to the start after copying the file:

...

for (int x{ 0 }; x <= 10; ++x) {
    std::string name{ "main" + std::to_string(x) + ".exe" };

    std::ofstream out(name, std::ios::binary);
    out << buf;
    out.close();
    from.seekg(0, std::ios::beg); // need to go back to the start here
}

...

You could simply use the std::filesystem standard library functionality for this though:

int main() {
    std::filesystem::path input("main.exe");

    for (int x{ 0 }; x <= 10; ++x) {
        std::filesystem::path outfile("main" + std::to_string(x) + ".exe");

        std::filesystem::copy_file(input, outfile, std::filesystem::copy_options::overwrite_existing);
    }

    return 0;
}