C++高精度性能測试函数

       在实际software开发工作中。我们常常会測试某个module或者function的执行效率。或者是某个算法的时间复杂度(尽管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，能够測试其复杂度)。这时候就须要精确获取时间。才干够准确的执行时间。以下的函数实现了精确计时，计时精度能够达到微秒级；可用于測试某个模块的效率！

//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 500
inline void FileTrace(IN LPCTSTR szFormat, ...)
{
	if (szFormat == NULL)
		return;

	TCHAR t_trace[_Trace_Size] = { _T('') };
	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);
}
#else
inline void FileTrace(IN LPCTSTR szFormat, ...){}
#endif

LARGE_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("*********************************************************************************
"));
	FileTrace(_T("Test result is as follow :
time: %I64x, %.3fms, %.3fms
"), (ULONGLONG)0, Time0, Time1);
	FileTrace(_T("*********************************************************************************
"));
    system("pause");
	return 0;
}

test result is ：