C++14几种计时方法的对比

1.C++14 版本，程序如下：

#include<iostream>
#include<ctime>
#include<time.h>
#ifdef _WIN32
#include <Windows.h>
#else
#include <unistd.h>
#endif
using namespace std;

void disptime(const struct tm* ptm);
int main()
{
	time_t nowtime;
	nowtime = time(NULL);
	cout << nowtime << endl;
	char* dt = ctime(&nowtime);

	cout << "本地日期和时间：" << dt << endl;
	tm* gmtm = gmtime(&nowtime);
	dt = asctime(gmtm);
	cout << "utc日期和时间：" << dt << endl;

	tm* itm = localtime(&nowtime);
	cout << "年：" << 1900 + itm->tm_year << endl;
	cout << "月：" << 1 + itm->tm_mon << endl;
	cout << "日：" << itm->tm_mday << endl;
	cout << "时间：" << itm->tm_hour << ":";
	cout << itm->tm_min <<" :";
	cout << itm->tm_sec << endl;
	 
	//方法1
	double beginTime = clock();
	Sleep(200); //ms
	double endTime = clock();
	cout << (endTime - beginTime)<<"ms" << endl;
	
	//方法2
	double start = GetTickCount(); //计时器
	Sleep(200);
	double end = GetTickCount();
	double last = end - start;
	cout << last << "ms" << endl;

	//方法3
	LARGE_INTEGER cpuFreq1;
	LARGE_INTEGER startTime1;
	LARGE_INTEGER endTime1;

	QueryPerformanceFrequency(&cpuFreq1);
	QueryPerformanceCounter(&startTime1);
	Sleep(200);
	QueryPerformanceCounter(&endTime1);
	double last1 = (((endTime1.QuadPart - startTime1.QuadPart) * 1000000) / cpuFreq1.QuadPart);
	cout << last1 << " us" << endl;

	return 0;
}

2.VS如报错请做如下设置：

3.结论：
对比发现，Windows 环境下C++计时误差大概率下在10ms以内；10ms内的计时误差大概率超过10ms。