程序代码：

int    printf (const char *__restrict, ...);
typedef unsigned long clock_t;
clock_t clock(void);


int main()
{
    clock_t start,finish;
    start=clock();
    for(int x=0;x<100000;x++) printf("%8d",x);
    finish=clock();
    printf("\n屏显10w次空循环，耗时：");
    printf("%.3lf 秒\n",((double)finish-start)/1000);
    return 0;
}