例程一、遞歸 實現N的階乘 例程

1. 例程功能：實現N的階乘。

2. 代碼如下：

#include <stdio.h>

static int recursive(int number);
int main ()
{
    int num = 1, sum = 0;

    printf("please input a number.\n");
    scanf("%d", &num);
    if (sum < 0)
      printf("please input a positive.\n");
    else
      printf("%d! = %d\n", num, recursive(num));

    return 0;
}
static int recursive(int number)
{
    printf("in number = %d \n", number);
    if (number < 0)
      return -1;
    if (!number)
      return 0;
    if (number == 1)
      return number;
    if (number > 1)
      return number*recursive(number-1);
}

編譯，運行：