lst-0644-book.cpp
// https://godbolt.org/z/Kxrz5ETh6
#include <concepts> // integral, floating_point
#include <iostream>
using namespace std;
int64_t trunc_to_10(integral auto val) { return (val/10)*10; }
int64_t trunc_to_10(floating_point auto val) { return int64_t(val/10)*10; }
int main() {
cout << trunc_to_10(144) << '\n'; // Ausgabe: 140
cout << trunc_to_10(122.2) << '\n'; // Ausgabe: 120
}