001.linux下clock()检测程序运行时间

 #include <stdio.h>
 #include <time.h>

 int main()
 {
     int i;
     int k;
     clock_t start,end;  //clock_t类型实际上为long int类型(4字节)
     printf("%d\n",sizeof(long int));
     start = clock();
     printf("start:%d\n",start);
     for(i=; i<; i++) ;
     end = clock();
     printf("end:%d\n",end);
     printf("%.3fs\n",(double)(end-start)/CLOCKS_PER_SEC); //linux下CLOCKS_PER_SEC=1000000
 }

运行结果：

4
start:0
end:20000
0.020s