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

void mv(std::string const &fname_from, std::string const &fname_to) {

    std::ifstream from(fname_from, std::ios_base::in | std::ios_base::binary); // open file for reading
    if (!from) {
        std::cerr << "Can't open " << fname_from << " for reading.\n";
        throw 1;
    }

    std::ofstream to(fname_to, std::ios_base::out | std::ios_base::trunc | std::ios_base::binary);
    if (!to) {
        std::cerr << "Can't open " << fname_to << " for writing.\n";
        throw 1;
    }

    char c;
    while (from.get(c))
        if (!to.put(c)) {
            std::cerr << "Error writing to " << fname_to << '\n';
            throw 1;
        }
}

int main() {
    mv ("a.exe", "b.exe");
}