编辑代码

#include <stdio.h>
int main ()
{
   int fac(int n);
   int n;
   int y;
   printf("input is numbren:");
   scanf("%d",&n);
   y=fac(n);
   printf("%d! is %d\n",n,y);
   return 0;
}
int fac(int n)
{
    int c;
    if(n==1||n==0)
      c=1;
      else 
      c=n*fac(n-1);
      return c;
}