#include<stdio.h>
int main(int argc,char **argv)
{
    int n,factorial=1;
    printf("please input an interger >= 0\n");
    scanf("%d",&n);
    while(n>0)
    {
        factorial*=n;
        n--;
      }
     printf("factorial of %d is :%d\n",n,factorial);
return 0;
}
/*printf输出时第一个%d显示的是0.Ubuntu 13.04环境下。怎么回事啊？*/