how to format big numbers with commas in c++

#include <iostream>
#include <iomanip>
#include <locale>

int main() {
    long long bigNumber = 1234567890123456LL;

    // Create a locale with the classic numeric formatting
    std::locale classicLocale("en_US.utf8");

    // Set the locale to classic numeric formatting
    std::cout.imbue(classicLocale);

    // Output the big number with commas
    std::cout << std::fixed << std::setprecision(0) << bigNumber << std::endl;

    return 0;
}