程序代码：

#include <stdio.h>
int f (int n)
{   
    if (n != 1)
    return  f(n-1)*n;
     else
    return 1;
    }
main ()
{   
    int i;
    while (scanf ("%d",&i))
    printf ("%d\t",f (i));
    getch ();
    }