递归,算法可能出错

Question

我正在做一个简单的程序C,5位数字的数字之和.虽然我用一个简单的函数完成它但我也需要用递归来做.我已经在网上阅读了很多关于这个问题的解决方案,使用递归和已经实现了我的一个.但这是错误的,我无法弄清楚我在算法中做了什么网格.

#include<stdio.h>
int sum5(int x);  //function for sum of  digits of 5 digit number

int main()
{
   int x;
   int result;
   printf("Enter a 5 digit number : ");
   scanf("%d",&x);
   printf("Number entered by you is %d",x);
   result = sum5(x);
   printf("Sum of digits of 5 digit number is = %d",&result);
   return 0;
}

int sum5(int x)
{
   int r;
   int sum=0;
   if(x!=0){
      r=x%10;
      sum=sum+r;
      x=x-r;      //doing this so that 0 come in the last and on diving it by 10, one digit will be removed.
      sum5(x/10);
   }
   return sum;
}

但在执行后我得到了错误的结果.它在输出上倾倒了一些匿名值.

Answer 1

这是不正确的,它是打印地址的result,而不是它的价值:

printf("Sum of digits of 5 digit number is = %d",&result);

改成:

printf("Sum of digits of 5 digit number is = %d", result);

始终检查结果scanf()以确保读取有效值:

/* Returns number of assignments made. */
if (scanf("%d", &x) == 1 && x > 9999 && x < 100000)
{
}

加上Osiris sum5()指出的执行错误.

Answer 2

此外,您的sum5功能不正确.您必须将值添加sum5到sum调用方函数的变量中.

int sum5(int x)
    {
        int r;
        int sum = 0;
        if (x != 0) {
            r = x % 10;
            sum = r;
            //x = x - r;  - this isn't required. integer division will floor x
            sum += sum5(x / 10);
        }
        return sum;
    }