java - 在Java中求和和反转单个输入的方法？

Question

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Answer 1

您的代码有问题：

您永远不会将用户输入放在 num 数组中，而 for 循环只是一个主动等待，

现在就试试：

public static void main(String[] args) 
            {
                //call for input
                System.out.println("Please Enter a 3-digit number..");
                Scanner in = new Scanner(System.in);
                int val = in.nextInt();
                int[] num = new int[3];
                if(val<=99) // is not a 3 digit number
                   return;

                int i =2;
                while (val > 0) {
                   num[i]=(val%10);
                   val = val / 10;
                   i--;
                }
                System.out.println("The Sum of the numbers is " + (num[0] + num[1]+ num[2]));
                System.out.println("The Reverse of the numbers is " + num[2] +""+ num[1]+""+ num[0]);

            }

输入 1 - 2 -3 为您提供：

Please Enter a 3-digit number..
1
2
3
The Sum of the numbers is 6
The Reverse of the numbers is 321

Answer 2

尝试这个

    Scanner in = new Scanner(System.in);
    int n = in.nextInt();
    int sum = 0;
    int rev = 0;
    while (n > 0) {
        int rem = n % 10;
        sum += rem;
        rev = rev * 10 + rem;
        n = n / 10;
    }
    System.out.println("The Sum of the numbers is " + sum);
    System.out.println("The Reverse of the numbers is " + rev);