Do while循环（Java）

Question

我想写一个程序，把每4位数字的每一位相加。例如，我从1000开始，加上1001，千变成2，百变成0，十变成0，单位变成1。这将持续增加每个数字，直到达到9999。这是我的代码，它只输出9999。

int num = 1000, unit = 0, ten = 0, hundred = 0, thousand = 0, newNum = 0, sumth = 0, sumh = 0, sumten = 0, sumu = 0;

while (num <= 9999)
{
    unit = num%10;
    newNum = num/10;
    ten = newNum%10;
    newNum=newNum/10;
    hundred = newNum%10;
    thousand = newNum/10;
    num++;
}
sumth = thousand + sumth;
sumh = hundred + sumh;
sumten = ten + sumten;
sumu = unit + sumu;

System.out.println(sumth + " " + sumh + " " + sumten + " " + sumu);

Answer 1

当循环时，它应该在内移动

while (num <= 9999)
    {
        unit = num%10;
        newNum = num/10;
        ten = newNum%10;
        newNum=newNum/10;
        hundred = newNum%10;
        thousand = newNum/10;

        sumth = thousand + sumth;
        sumh = hundred + sumh;
        sumten = ten + sumten;
        sumu = unit + sumu
        num++;    

    }


输出：45000405004050040500
工作链接：https://ideone.com/WrAX8D

Answer 2

为了便于阅读，稍微整理一下：

int num = 1000,
    sumThousands = 0,
    sumHundreds = 0,
    sumTens = 0,
    sumUnits = 0;

    while (num <= 9999)
    {
        int units = num % 10;
        int tens = (num / 10) % 10;
        int hundreds = (num / 100) % 10;
        int thousands = (num / 1000) % 10;

        sumUnits += units;
        sumTens += tens;
        sumHundreds += hundreds;
        sumThousands += thousands;

        num++;
    }

System.out.println(sumThousands + " " + sumHundreds + " " + sumTens + " " + sumUnits);

您将获得的输出是：

45000 40500 40500 40500

这是预期的。对于整数序列1000...9999：

• 在“千”列中，每个数字都是1。。9重复1000次

• 所以其他列的和是900(9 8 7 6 5 4 3 2 1) = 900(9(10)/2) = 40500