C++测试代码运行时间的模板

#include <iostream>
#include <chrono>
#include <ctime>

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


    using _time = steady_clock::time_point;

    _time t1 = steady_clock::now();

    /*code one*/

    _time t2 = steady_clock::now();



    
    /*code two*/

    _time t3 = steady_clock::now();
    duration<double> time_span1 = duration_cast<duration<double>>(t2 - t1);
    duration<double> time_span2 = duration_cast<duration<double>>(t3 - t2);
    std::cout << "It took me " << time_span1.count() << " seconds." << endl;
    std::cout << "It took me " << time_span2.count() << " seconds." << endl;

    return 0;
}
//可能会有小误差，建议使用大数据测试以减少误差

 封装如下

#include <iostream>
#include <chrono>


struct Timer{
    std::chrono::time_point<std::chrono::steady_clock> start, end;
    std::chrono::duration<double> duration;

    Timer(){
        start = std::chrono::high_resolution_clock::now();
    }

    ~Timer(){
        end = std::chrono::high_resolution_clock::now();
        duration = end - start;

        double ms = duration.count() * 1000.0;
        std::cout << "It takes me :" << ms << " ms" << std::endl;
    }

};

 获取当前时间

void get_now_time() {
    const auto now = system_clock::now(); /* Possible output: */
    const time_t now_time_t = system_clock::to_time_t(now);
    std::cout << ctime(&now_time_t) << '
';  // Wed Oct 21 16:29:00 2015
}