c++程序运行时间总结

#include <iostream>
#include <Windows.h>
#include<time.h>
#include <iomanip>

using namespace std;

void timeConsuming()
{
int i  = 100;
while (i > 0)
{
Sleep(10);
i--;
}
}

// 利用clock()函数实现程序时间的统计，其中start_time 表示此进程从开始运行到开始
//统计时间所用过的时间，然后利用CLOCKS_PER_SEC获取实际时间，统计精度为 毫秒；
void clock_t_type()
{
clock_t start_time , end_time;
start_time = clock();
timeConsuming();
end_time = clock();

//此处注意 clock_t 为long 类型，在进行相除的时候若想获得精确时间，需要分子强制类型转换为double类型。
double duration = (double)(end_time - start_time)/CLOCKS_PER_SEC;
cout  << left << setw(25) <<setfill(' ') << "clock type : " ;
cout  << duration << " seconds"  << endl;
}

// GetTickCount返回从系统启动到当前的时间，单位为毫秒 , 可以和Sleep 函数结合使用
// 若系统运行时间超过49.71天时，这个数就会归0，
void GetTickCount_Type()
{
DWORD start_time , end_time , duration;
start_time = GetTickCount();
timeConsuming();
end_time  = GetTickCount();

duration = end_time  -  start_time;
cout  << left << setw(25 )  << setfill(' ') << "GetTickCount type : ";
cout  << duration/1000.0 << " seconds" << endl;

}

// QueryPerformanceFrequency 高精度计时器 ;类型：Win32API
// 要求计算机从硬件上支持高精度定时器。
// 返回值的单位为 秒
void QueryPerformanceFrequency_type()
{
LARGE_INTEGER time_start;
LARGE_INTEGER time_end;
LARGE_INTEGER current_f;
double frequency;

QueryPerformanceFrequency(¤t_f); 	// 作用：返回硬件支持的高精度计数器的频率。
frequency = current_f.QuadPart;
QueryPerformanceCounter(&time_start);
timeConsuming();
QueryPerformanceCounter(&time_end);

double duration = (time_end.QuadPart - time_start.QuadPart)/frequency;

//cout << "frequency : "  << frequency << endl;
//cout << "time start : " << time_start << endl;
//cout << "time_end : " << time_end << endl;
cout  << left << setw(25 ) << setfill(' ');
cout  <<  "QueryPerformance time: "  << duration <<":seconds" << endl;
}
//The time function returns the number of seconds elapsed since midnight (00:00:00), January 1, 1970,
//Coordinated Universal Time (UTC),  单位：秒
void time_type()
{
time_t time_start , time_end;
time_start = time(NULL);
timeConsuming();
time_end = time(NULL);
cout  << left << setw(25 ) << setfill(' ');
cout  <<  "time_type time: "  << (time_end - time_start) <<":seconds" << endl;
}

// 利用 GetLocalTime 获取当前的年月日
void get_current_time()
{
SYSTEMTIME sys;
GetLocalTime(&sys);
cout<<sys.wYear<<"年";
cout<<sys.wMonth<<"月";
cout<<sys.wDay<<"日";
cout<<sys.wHour<<"时";
cout<<sys.wMinute<<"分";
cout<<sys.wSecond<<"秒";
cout<<sys.wMilliseconds<<"毫秒";
cout<<",星期"<<sys.wDayOfWeek<<endl;
}

int main()
{
get_current_time();
clock_t_type();
GetTickCount_Type();
QueryPerformanceFrequency_type();
time_type();

return 0;

}