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
",sizeof(long int));
    start = clock();
    printf("start:%d
",start);
    for(i=0; i<10000000; i++) ;
    end = clock();
    printf("end:%d
",end);
    printf("%.3fs
",(double)(end-start)/CLOCKS_PER_SEC); //linux下CLOCKS_PER_SEC=1000000
}

运行结果：

4
start:0
end:20000
0.020s