#include <time.h>
#include <stdio.h>
#include <dos.h>
#include <conio.h>
#include <windows.h>
#include <windowsx.h>
#include <fstream.h>
#include <iostream.h>
int main(void)
{int i,j;
int wrh,v,s=1500;

clock_t start,end;
start=clock();
cout<<start<<"\n";

for(i=0;i<50000;i++)
{j+1;j-1;}
end=clock();
cout<<end<<"\n";
getch();
}

MSDN上的例子，好好看一下。
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

void sleep( clock_t wait );

void main( void )
{
long i = 600000L;
clock_t start, finish;
double duration;

/* Delay for a specified time. */
printf( "Delay for three seconds\n" );
sleep( (clock_t)3 * CLOCKS_PER_SEC );
printf( "Done!\n" );

/* Measure the duration of an event. */
printf( "Time to do %ld empty loops is ", i );
start = clock();
while( i-- )
;
finish = clock();
duration = (double)(finish - start) / CLOCKS_PER_SEC;
printf( "%2.1f seconds\n", duration );
}

/* Pauses for a specified number of milliseconds. */
void sleep( clock_t wait )
{
clock_t goal;
goal = wait + clock();
while( goal > clock() )
;
}

你用的50000值太小了,计算滴答数又不正确.

clock函数告诉调用进程用了多少处理器时间,
秒时间是时钟返回值除以该常量值的近似值
.换句话说,clock返回值为已经消逝的处理器时钟滴答数,
一个时钟滴答数近似等于1/CLOCKSPERSEC
秒.

#include <time.h>
#include <stdio.h>
#include <dos.h>
#include <conio.h>
#include <windows.h>
#include <windowsx.h>
#include <fstream.h>
#include <iostream.h>
int main(void)
{int i,j;
int wrh,v,s=1500;

clock_t start,end;
double duration;
start=clock();
cout<<start<<"\n";

for(i=0;i<50000000;i++)
{j+1;j-1;}
end=clock();
duration=(double)(end-start)/CLOCKS_PER_SEC;
cout<<duration<<"\n";
getch();
}

真的是呀,谢谢

请教一下，最后的那个sleep函数有什么用？函数中的while语句是判断什么，有什么用？

[此贴子已经被作者于2006-3-28 15:54:21编辑过]

一个时钟滴答数为1/CLOCK_PER_SEC,
CLOCK_PER_SEC个滴答数(CLOCK_PER_SEC*1/CLOCK_PER_SEC)为一秒,
3*CLOCK_PER_SEC为参数意思就是3秒.
goal=wait+clock();意思就是当前的时钟滴答数加上3秒,
while(goal>clock());不断增加处理器时钟滴答数,当时钟滴答数goal==clock()时
完成(也就经过3秒).

hao