C++高精度性能测试函数

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在实际software开发工作中，我们经常会测试某个module或者function的执行效率。或者是某个算法的时间复杂度(虽然时间复杂度一定程度上依赖于机器性能，但在同一台computer上，经过算法优化，可以测试其复杂度)；这时候就需要精确获取时间，才可以准确的运行时间，下面的函数实现了精确计时，计时精度可以达到微秒级；可用于测试某个模块的效率！

//Purpose :this programme is designed for testing the performance of your code ,some function ect,//it can show the time of spending on your running on it . it is  beneficial to improve your performance //of code// author :Jackery_shh// data: July 8th  2015#include<Windows.h>#include<iostream>#include<tchar.h>using namespace std;#define  IN#ifdef _DEBUG #define _Trace_Size 500inline void FileTrace(IN LPCTSTR szFormat, ...){if (szFormat == NULL)return;TCHAR t_trace[_Trace_Size] = { _T('\0') };va_list vl = NULL;// 生成内容va_start(vl, szFormat);_vsntprintf_s(t_trace, _Trace_Size, _TRUNCATE, szFormat, vl);va_end(vl);OutputDebugString(t_trace);}#elseinline void FileTrace(IN LPCTSTR szFormat, ...){}#endifLARGE_INTEGER begin_time ,freq;int main(){LARGE_INTEGER begin_time ,freq;QueryPerformanceFrequency (&freq);QueryPerformanceCounter (&begin_time);    //begin time      for (long test0=0;test0<5000000;test0++)     { test0=test0+1;     }LARGE_INTEGER end_time0;  QueryPerformanceCounter (&end_time0);//after runnin the 'for' loop statement,the time is Time0 double Time0 = ((double) (end_time0.QuadPart - begin_time.QuadPart)*1000.0) / (double) (freq.QuadPart);    int test1=10000;while (test1){test1--;} LARGE_INTEGER end_time1; QueryPerformanceCounter (&end_time1); double Time1 = ((double) (end_time1.QuadPart - begin_time.QuadPart)*1000.0) / (double) (freq.QuadPart);    FileTrace(_T("*********************************************************************************\n"));FileTrace(_T("Test result is as follow :\ntime: %I64x, %.3fms, %.3fms\n"), (ULONGLONG)0, Time0, Time1);FileTrace(_T("*********************************************************************************\n"));    system("pause");return 0;}

test result is ：

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