std::chrono::system_clock::now

#include <chrono>
#include <iostream>
 
int main()
{
    const auto now = std::chrono::system_clock::now();
    const std::time_t t_c = std::chrono::system_clock::to_time_t(now);
    std::cout << "系统时钟当前为 " << std::ctime(&t_c);
}