c语言 计时执行时间

#include<stdio.h>

#include<time.h>

 int main()

{

 struct timeval start,end;
 double timeuse;
 gettimeofday( &start, NULL );

 

 //****被测试点******

 

 gettimeofday( &end, NULL );
 timeuse = 1000000 * ( end.tv_sec - start.tv_sec ) + end.tv_usec - start.tv_usec;
 timeuse /= 1000000;
 printf("%.4f\n",timeuse);

 }