C和C++篇——各种各样的函数

时间函数

#include <windows.h>                //取系统时间
LARGE_INTEGER tick, begin, end;
QueryPerformanceFrequency(&tick);	//取计数器频率
QueryPerformanceCounter(&begin);	//取初始硬件定时器计数
//中间程序运行//
QueryPerformanceCounter(&end);      //获得终止硬件定时器计数
cout << "计数器频率：" << tick.QuadPart << "Hz" << endl;
cout << "时钟计数  ：" << end.QuadPart - begin.QuadPart << endl;
cout << setprecision(6) << (end.QuadPart - begin.QuadPart) / double(tick.QuadPart) << "秒" << endl;

延时循环

#include<ctime>
不啦不啦
float secs;
cin>>secs;
clock_t delay=secs*CLOCK_PER_SEC;
clock_start=clock();                
while(clock()-start<delay)          
     ;                               //空语句

————数学函数————

向下取整函数floor(x)：

返回不超过x的最大整数。