遍历数字中的每个数字 [英] Iterate through each digit in a number

问题描述

我正在尝试创建一个程序，用于判断给定的数字是否为 Happy Number 或不。找到一个快乐的数字需要将数字中的每个数字平方，并将每个数字的平方结果加在一起。

I am trying to create a program that will tell if a number given to it is a "Happy Number" or not. Finding a happy number requires each digit in the number to be squared, and the result of each digit's square to be added together.

在Python中，你可以使用这样的东西：

In Python, you could use something like this:

SQUARE[d] for d in str(n)

但是我找不到如何在Java中迭代数字中的每个数字。正如你所知，我是新手，并且在Java文档中找不到答案。

But I can't find how to iterate through each digit in a number in Java. As you can tell, I am new to it, and can't find an answer in the Java docs.

推荐答案

你可以使用模10运算得到最右边的数字，然后将数字除以10得到下一个数字。

You can use a modulo 10 operation to get the rightmost number and then divide the number by 10 to get the next number.

long addSquaresOfDigits(int number) {
    long result = 0;
    int tmp = 0;
    while(number > 0) {
        tmp = number % 10;
        result += tmp * tmp;
        number /= 10;
    }
    return result;
}

您也可以将其放入字符串并将其转换为char数组迭代它做类似 Math.pow（charArray [i] - '0'，2.0）;

You could also put it in a string and turn that into a char array and iterate through it doing something like Math.pow(charArray[i] - '0', 2.0);

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