DigitsIterator.php

<?php

class DigitsIterator implements Iterator {

    private $num;

    private $radix;

    private $temp;

    private $key;

    public function __construct($num, $radix = 10) {
        $this->num = $num;
        $this->radix = $radix;
    }

    public function current() {
        return $this->temp % $this->radix;
    }
    
    public function key() {
        return $this->key;
    }
    
    public function next() {
        $this->temp = floor($this->temp / $this->radix);
        $this->key++;
    }

    public function rewind() {
        $this->temp = $this->num;
        $this->key = 0;
    }

    public function valid() {
        return $this->temp > 0;
    }

}