Online PHP editor | refs for 9EimB

<?php define('ALNUM_MAP', str_split('abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789')); define('DIGIT_MAP', array_flip(ALNUM_MAP)); function numToAlnum($num) { return strtr($num, ALNUM_MAP); } function alnumToNum($alphaNum) { return strtr($alphaNum, DIGIT_MAP); } $ids = ['4440', '464426', '43304441302845', '262018191701180', '273381111186152545352']; foreach ($ids as $id) { $idLength = strlen($id); $alphaNum = numToAlnum($id); $alNumLength = strlen($alphaNum); $backToId = alnumToNum($alphaNum); var_export(['original' => $id, 'encoded' => $alphaNum, 'decoded' => $backToId, 'reduction' => $idLength - $alNumLength]); echo "\n---\n"; }