PAT基础编程题目集 4-8 简单阶乘计算

#include <stdio.h>int Factorial( const int N );int main(){    int N, NF;    scanf("%d", &N);    NF = Factorial(N);    if (NF)  printf("%d! = %d\n", N, NF);    else printf("Invalid input\n");    return 0;}int Factorial( const int N ){    int i,fac=1;    if(N>=0)    {      for(i=1;i<=N;i++)         fac*=i;         return fac;    }    else    return 0;}