我怎么知道我的 `std::chrono::high_resolution_clock` 对应于 `steady_clock` 或 `system_clock` 的别名，或其他？

Question

How can I know my std::chrono::high_resolution_clock correspond to the alias of steady_clock or system_clock , or other?

Many websites and books are providing examples using the system_clock , that might be goes back due to the synchronization, to measure the time spent for a function. I don't think that is the good idea to measure the time. Instead, I think we should use std::chrono::steady_clock .

Sometimes std::chrono::high_resolution_clock is used. According to the URL https://en.cppreference.com/w/cpp/chrono/high_resolution_clock , it says "It may be an alias of std::chrono::system_clock or std::chrono::steady_clock , or a third, independent clock."

So, I want to know how can I check which aliases my std::chrono::high_resolution_clock correspond to. Any ideas?

Answer 1

Directly from Sam Varshavchik's comment. You can use std::is_same from <type_traits> to check if two types are the same.

Here's an example for checking the three standard clocks in chrono :

#include <chrono>
#include <iostream>
#include <type_traits>

int main() {
    using namespace std::chrono;

    std::cout << std::boolalpha
        << std::is_same_v<system_clock, high_resolution_clock> << '\n'
        << std::is_same_v<system_clock, steady_clock> << '\n'
        << std::is_same_v<high_resolution_clock, steady_clock> << '\n'
    ;
}

Demo