程序运行时间

/***用高精度计时器,毫秒为单位***/
#include <iostream>
#include <windows.h>
using namespace std ;

int main(void)
{
 LARGE_INTEGER BegainTime ; 
 LARGE_INTEGER EndTime ; 
 LARGE_INTEGER Frequency ;
 QueryPerformanceFrequency(&Frequency);
 QueryPerformanceCounter(&BegainTime) ;
 //要测试的代码放在这里
 QueryPerformanceCounter(&EndTime) ;
 cout << ( EndTime.QuadPart - BegainTime.QuadPart )*1000 / Frequency.QuadPart ;

 system("pause") ;
 return 0 ;
}
以下微秒为单位

#include <iostream>
#include <Windows.h>
using namespace std;
class timer    
{  
	/***微秒为单位***/
public:  
	timer()
	{  
	QueryPerformanceFrequency(&m_i64CPUFreq);  
	}  

	~timer()
	{

	}

	void start(void)
	{
		reset();  
		QueryPerformanceCounter(&m_i64Begin);
	} 

	void end(void)
	{
		QueryPerformanceCounter(&m_i64End);
	}

	DWORD getTime(void) const
	{
		DWORD dwTotalMicrosecond = 0;  
		LARGE_INTEGER i64TickCount;  
		i64TickCount.QuadPart = m_i64End.QuadPart - m_i64Begin.QuadPart;  
		dwTotalMicrosecond = (DWORD) (i64TickCount.QuadPart * 1000000 / m_i64CPUFreq.QuadPart);  

		return dwTotalMicrosecond;  
	}

private:  
	LARGE_INTEGER m_i64CPUFreq;   
	LARGE_INTEGER m_i64Begin;  
	LARGE_INTEGER m_i64End;  
	void reset(void)
	{
			m_i64Begin = m_i64End;
	}
};  
/***测试例子***/
int main()   
{  
	timer t;  
	t.start(); 

	{  
		for(int i = 0; i < 1000000; i++)  
		{  
			int n = i;  
		}  
	}  

	t.end();  

	cout<<t.getTime()<<endl;
	return 0;
}