C++中clock()函数的使用

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函数声明：clock_t clock( void );

clock_t 是 long 型，typedef long clock_t;

clock（）使用的头文件是：time.h

CLOCK_PER_SEC表示每一秒经历的时钟数。通常我们用clock_t now = clock(); while(i--); finish = clock(); seconds = (finish - now)/CLOCK_PER_SEC; seconds表示进程持续的时间。

例如MSDN中一个clock()的例子：

#include"time.h"#include"stdlib.h"#include"stdio.h"void sleep( clock_t wait );void main( void ){  long    i = 600000L;  clock_t start, finish;  double  duration;   printf( "Delay for three seconds\n" );  sleep( (clock_t)3 * CLOCKS_PER_SEC );  printf( "Done!\n" );   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 );}void sleep( clock_t wait ){  clock_t goal;  goal = wait + clock();  while( goal > clock() )     ;}

Output
Delay for three seconds Done! Time to do 600000 empty loops is 0.1 seconds

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