可以精確計時到微秒的類

//ElapsedTime.h
#ifndef _ELAPSED
#define _ELAPSED

class CElapsed
{
public:
    CElapsed();

    bool Begin();
 
    double End(); //停止計數
 
    bool Available();//是否可調用這兩個函數

    _int64 GetFreq();
    _int64 GetBeginTime();
    void SetBeginTime( _int64 bgTime );
   
private:
    int Initialized;
    _int64 Frequency;
    _int64 BeginTime;
};
#endif

 

 

 

//ElapsedTime.cpp

//另外gettickcount()這個函數也是可以精確到ms的
#include <stdafx.h>
#include "ElapsedTime.h"

CElapsed::CElapsed()
{
    Initialized = QueryPerformanceFrequency((LARGE_INTEGER *)&Frequency);
}

bool CElapsed:: Begin()
{
    if(!Initialized)
    {
        return 0; //某些CPU不運行此函數調用
    }
    return QueryPerformanceCounter((LARGE_INTEGER *)&BeginTime);
}

double CElapsed::End() //停止計數
{
    if(!Initialized)
    {
        return 0.0; //某些CPU不運行此函數調用
    }
    _int64 endtime;

    QueryPerformanceCounter((LARGE_INTEGER *)&endtime);

    _int64 elapsed = endtime - BeginTime;
   
//    return (double)elapsed / (double)Frequency;

  TRACE("%f/n",(double)elapsed / (double)Frequency);
     CString str;
  str.Format("%f",(double)elapsed / (double)Frequency);
  AfxMessageBox(str);

    return 0;
}

bool CElapsed::Available()//是否可調用這兩個函數
{
    return Initialized;
}

_int64 CElapsed::GetFreq()
{
    return Frequency;
}

_int64 CElapsed::GetBeginTime()
{
    return BeginTime;
}

void CElapsed::SetBeginTime( _int64 bgTime )
{
    BeginTime = bgTime;
}

 

 

 

 

// demo

 CElapsed m_elapsed;
 m_elapsed.Begin();

// 希望計時的代碼
 m_elapsed.End();