C++ 精确计时类

微秒级别

例子：

#include<iostream>
using namespace std;
///////////
#ifndef __MyTimer_H__
#define __MyTimer_H__
#include <windows.h>

class MyTimer{
private:
    int _freq;
    LARGE_INTEGER _begin;
    LARGE_INTEGER _end;
public:
    long costTime;            // 花费的时间(精确到微秒)
public:
    MyTimer(){
        LARGE_INTEGER tmp;
        QueryPerformanceFrequency(&tmp);
        _freq = tmp.QuadPart;
        costTime = 0;
    }
    void Start(){            // 开始计时
        QueryPerformanceCounter(&_begin);
    }
    void End(){                // 结束计时
        QueryPerformanceCounter(&_end);
        costTime = (long)((_end.QuadPart - _begin.QuadPart) * 1000000 / _freq);
    }
    void Reset(){            // 计时清0
        costTime = 0;
    }
};
#endif 
/////////////////
int main(){
	MyTimer mt;
	mt.Start();
	int i;
	int sum=0;
	for(i=0;i<12345678;i++){
		sum=sum+i;
	}
	mt.End();
	cout<<"Total cost time:"<<mt.costTime<< " us" << endl;
	return 0;
}