windows下的精确计时函数

BOOL QueryPerformanceFrequency(LARGE_INTEGER *lpFrequency)获取系统的计数器的频率

BOOL QueryPerformanceCounter(LARGE_INTEGER *lpPerformanceCount)获取计数器的值

(原文出处： coder_xia的博客：http://blog.csdn.net/coder_xia/article/details/6566708)

   然后用两次计数器的差除以Frequency就得到时间。

测试程序如下：

 #include <iostream>
 #include <windows.h>
 using namespace std;
 int main()
 {
     LARGE_INTEGER m_nFreq;
     LARGE_INTEGER m_nBeginTime;
     LARGE_INTEGER nEndTime;
     QueryPerformanceFrequency(&m_nFreq); // 获取时钟周期
     QueryPerformanceCounter(&m_nBeginTime); // 获取时钟计数
     Sleep(100);
     QueryPerformanceCounter(&nEndTime);
     cout << (double)(nEndTime.QuadPart-m_nBeginTime.QuadPart)*1000/m_nFreq.QuadPart << endl;
 }

 

需要注意的就是结果需要强制转换为double，不然会得到如下错误：<< is ambiguous