VC中几个关于时间计算的函数

#include <iostream.h>
#include <windows.h>
#include <stdio.h>
#include <time.h>
void sleep( clock_t wait )
{
clock_t goal;
goal = wait + clock();
while( goal > clock() )
;
}
int main()
{
// 利用QueryPerformanceFrequency 和QueryPerformanceCounter 精确计算时间

LARGE_INTEGER litmp;
LONGLONG QPart1,QPart2;
QueryPerformanceFrequency(&litmp); // 获得CPU的频率
double dfMinus,dfFreq,dfTim;

// 获得计数器的时钟频率
dfFreq = (double)litmp.QuadPart;
cout<< "频率为:"<< dfFreq/1000000 <<"MHZ"<<endl;

QueryPerformanceCounter(&litmp);

// 获得初始值

QPart1 = litmp.QuadPart;
cout<<double(QPart1)<<endl;
/// 放入被测程序
Sleep(100);
// 结束被测程序
QueryPerformanceCounter(&litmp);

// 获得终止值

QPart2 = litmp.QuadPart;

cout<<double(QPart2)<<endl;

dfMinus = (double)(QPart2-QPart1);
dfTim = dfMinus / dfFreq;
// 获得对应的时间值
cout<< "cost time is :"<< dfTim*1000000 << " us "<<endl;
//CString s;
Format("my name is %6s","wind");
printf("%6.f",dfTim);
cout<<endl;

/******************* use clock *************************************************/
cout<< "*************use clock get the time************"<<endl;

clock_t start, finish;
long i = 600000L;

start = clock();
while( i-- );
finish = clock();
cout<< "Time is:" << (double)(finish - start)/CLOCKS_PER_SEC <<endl; //只能精确到ms级

/************************* use gettickgount()**********************************/

DWORD start_time = GetTickCount();

sleep( (clock_t)3 * CLOCKS_PER_SEC );

DWORD end_time = GetTickCount();

cout<< end_time-start_time <<endl; // 精确到ms

return 0;
}