用C写的计算运行时间

#include <stdio.h>

#include <stdlib.h>

#include <time.h>

int main( void )

{

   long     i = 10000000L;

   clock_t start, finish;

   double   duration;

   printf( "Time to do %ld empty loops is ", i );

   start = clock();

   while( i-- )       ;

   finish = clock();

   duration = (double)(finish - start) / CLOCKS_PER_SEC;

   printf( "%f seconds", duration );

   system("pause");

}