//********************************************************
// The following code example is taken from the book
//  C++23 - The Complete Guide
//  by Nicolai M. Josuttis (www.josuttis.com)
//  http://www.cppstd23.com
//
// The code is licensed under a
//  Creative Commons Attribution 4.0 International License
//  http://creativecommons.org/licenses/by/4.0/
//********************************************************


#include <iostream>
#include <locale>
#include <print>
#include <string>

// define facet of locale with thousands separator:
struct ThousandsSep : std::numpunct<char> {
  char do_decimal_point() const override { return '.'; }     // decimal point is dot
  char do_thousands_sep() const override { return ','; }     // separate with commas
  std::string do_grouping() const override { return "\3"; }  // every 3 digits
};

int main()
{
  // patch std::cout locale to use thousands separator:
  static std::locale locThSep{std::cout.getloc(), new ThousandsSep{}};
  std::cout.imbue(locThSep);

  // use locale to print numeric values:
  std::println("{:10} {:16}", 1000000, 123456.9999);               // locale not used
  std::println("{:10L} {:16L}", 1000000, 123456.9999);             // locale not used
  std::println(std::cout, "{:10L} {:16L}", 1000000, 123456.9999);  // locale used
}