以下所有代码都有使用Sleep()延时函数,需 #include <Windows.h>
1.使用clock(),ms级别计时器 :
double start = clock();
Sleep(1000);
double end = clock();
double last = start - end;
cout << last << "ms" << endl;
使用时需要包含头文件<ctime>
2. 使用GetTickCount(),ms级别计时器 :
double start = GetTickCount(); //计时器
Sleep(2000);
double end = GetTickCount();
double last = start - end;
cout << last << "ms" << endl;
使用时需包含<Window.h>
3.使用getTickCount(),ms级别计时器:
double start = getTickCount();//开始时间
Sleep(2000);
double end = getTickCount();
double last = (end - start) * 1000 / getTickFrequency();
cout << last << "ms" << endl;
这是opencv 所带计时器,使用时需#include <opencv2/opencv.hpp>,前面那个GetTickCount()是win的API。
4.使用time(NULL),s级别计时器:
double start, stop, durationTime;
start = time(NULL);
Sleep(2000);
stop = time(NULL);
durationTime = (double)difftime(stop, start);
cout << "程序耗时:" << durationTime << " s" << endl;
需要包含<ctime>
5.微秒级计时器QueryPerformance:
LARGE_INTEGER cpuFreq;
LARGE_INTEGER startTime;
LARGE_INTEGER endTime;
QueryPerformanceFrequency(&cpuFreq);
QueryPerformanceCounter(&startTime);
Sleep(1000);
QueryPerformanceCounter(&endTime);
double last = (((endTime.QuadPart - startTime.QuadPart) * 1000000) / cpuFreq.QuadPart);
cout << last << " us" << endl;
需要包含<Windows.h>
还可以将其封装为一个类:
class stop_watch
{
public:
stop_watch()
: elapsed_(0)
{
QueryPerformanceFrequency(&freq_);
}
~stop_watch() {}
public:
void start()
{
QueryPerformanceCounter(&begin_time_);
}
void stop()
{
LARGE_INTEGER end_time;
QueryPerformanceCounter(&end_time);
elapsed_ += (end_time.QuadPart - begin_time_.QuadPart) * 1000000 / freq_.QuadPart;
}
void restart()
{
elapsed_ = 0;
start();
}
//微秒
double elapsed()
{
return static_cast<double>(elapsed_);
}
//毫秒
double elapsed_ms()
{
return elapsed_ / 1000.0;
}
//秒
double elapsed_second()
{
return elapsed_ / 1000000.0;
}
private:
LARGE_INTEGER freq_;
LARGE_INTEGER begin_time_;
long long elapsed_;
};
int main()
{
stop_watch watch;
watch.start();
Sleep(2000);
watch.stop();
cout << watch.elapsed() << endl;
}
6.C++11 chrono库,微秒级别计时器
auto start = steady_clock::now();
Sleep(1000);
auto end = steady_clock::now();
auto last = duration_cast<microseconds>(end - start);
cout << last.count() << "um";
需要包含头文件 #include <chrono>并且using namespace std::chrono;