How to extract each digit from a number?

Question

All I can think of is to repeatedly divide the number by 10 (until number is less than 10) and keep a count, but is there a trick for this sort of thing?

Answer 1

Yep, you pretty much have the mathematical way to do it right there.

while (num >= 10)
    digit = num MOD 10   // and save this into an array or whatever
    num = num / 10

at the end of this, num will contain the last digit.

Here's a Javascript implementation:

function getDigits(num) {
    var digits = [];
    while (num >= 10) {
        digits.unshift(num % 10);
        num = Math.floor(num / 10);
    }
    digits.unshift(num);
    return digits;
}

Note that it only works for non-negative integers.