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C++ 之计时函数总结

• 总结Windows下C++开发时的计时实现

1. clock()

#include <time.h>　　　//引入头文件void main()
{clock_t start, end;start = clock();fun();  //需计时的函数end = clock();  float t_c=float(end-start)/CLOCKS_PER_SEC;cout << "func cost = " << t_c << "ms" << endl;  printf("func cost = %.3f ms", t_c);  
}

2. cv::getTickCount()

#include<iostream>
#include<opencv2/opencv.hpp>void main()
{double t1 = cv::getTickCount();func();double t2 = cv::getTickCount();double t_c = (t2 - t1)/cv::getTickFrequency();cout << "func cost = " << t_c << "ms" << endl;  printf("func cost = %.3f ms", t_c); 
}

3. std::chrono

#include <iostream>
#include <chrono>
void time4()
{// 计时开始时间点// chrone 中常用的时钟类:// 		- std::chrono::high_resolution_clock//   	- std::chrono::system_clock//      - std::chrono::steady_clock// 三种时钟类有一些区别，其中 high_resolution_clock 精度最高auto start = std::chrono::high_resolution_clock::now();// 要计时的代码段fun();  // 计时结束时间点auto end = std::chrono::high_resolution_clock::now();// 计算运行时间, 时间单位://      - std::chrono::seconds//      - std::chrono::milliseconds//      - std::chrono::microseconds//      - std::chrono::nanosecondsauto duration = std::chrono::duration_cast<std::chrono::microseconds> (end - start);// 输出时间(给定时间单位)cout << "elapsed time in chrono = " << duration.count()/1000.0 << "ms" << endl;
}