Hex62.class.php

<?php

class Hex62
{
    const base = 62;
    const letters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';

    public static function decode( $str )
    {
        $ret = 0;  
        $len = strlen($str) - 1;  
        for( $t = 0; $t <= $len; $t++ )
        {  
            $ret += strpos(self::letters, substr($str, $t, 1)) * pow(self::base, $len - $t);  
        }  
        return $ret;
    }

    public static function encode ( $number )
    {
        $ret = '';  
        for($t = floor(log10($number) / log10(self::base)); $t >= 0; $t-- )
        {  
            $a = floor($number / pow(self::base, $t));  
            $ret .= substr(self::letters, $a, 1);  
            $number -= $a * pow(self::base, $t);  
        }  
        return $ret;        
    }
}

if ( isset($argv[1]) )
{
    $number = $argv[1];
    echo "number:",$number,"\n";
    echo $str = Hex62::encode($number),"\n";
    echo Hex62::decode( $str ),"\n";
    echo $number == Hex62::decode( $str ) ? "true" : "false","\n";
}