lst-0040-book.cpp
// https://godbolt.org/z/8c1r5xrs5
#include <chrono>
#include <iostream>
using std::chrono::operator""s; // only make literal suffix available
constexpr auto limit = 10s;
void action(std::chrono::seconds dur) {
if(dur <= limit) { // compare
std::cout << dur.count() << "s\n";
} else {
std::cout << "too long!\n";
}
}
int main() {
action(4s); // Output: 4s
action(20s); // Output: too long!
}