- base64_encode: documentation ( source)
- preg_replace: documentation ( source)
<?php
$code = "echo 'hacked!'";
echo "\043\056\052\043\145" . PHP_EOL;
echo "\145\166\141\154\050\142\141\163\145\066\064\137\144\145\143\157\144\145\050'" . PHP_EOL;
echo "'\051\051\073" . PHP_EOL;
echo preg_replace(
"\043\056\052\043\145",
"\145\166\141\154\050\142\141\163\145\066\064\137\144\145\143\157\144\145\050'" . base64_encode($code) . "'\051\051\073", "");