sixtycoder.class.php

<?php
class SixtyCoder {
    public $table = '0123456789abcdefghijkmnopqrstuvwxyzABCDEFGHIJKLMNPQRSTUVWXYZ';
    
    public function to60($number = 0) {
        $number = (int) $number;
        $output = '';
        return $this->divide($number);
    }
    
    public function from60($letters = '0') {
        $length = strlen($letters);
        $number = 0;
        for ($i = 0; $i < $length; $i++) {
            $pos = strpos($this->table, $letters[$i]);
            if ($pos === false) {
                return 0;
            }
            $pow = $length - ($i+1);
            $number = $number + $pos * pow (60, $pow);
        }
        return $number;
    }
    
    public function divide($number = 0, $letters = '') {
        if ($number < 60) {
            $letters = $this->getLetter($number) . $letters;
        } else {
            $rest = $number % 60;
            $letters = $this->getLetter($rest) . $letters;
            $number = ($number - $rest) / 60;
            $letters = $this->divide($number, $letters);
        }
        return $letters;
    }
    
    public function getLetter($number) {
        return substr($this->table, $number, 1);
    }
}



$coder = new SixtyCoder();
echo $coder->to60(time()) . '<br>';
echo $coder->from60('241IVG') . '<br>';