- var_dump: documentation ( source)
- strpos: documentation ( source)
- base64_decode: documentation ( source)
<?php
$str = 'JzAwMDEyLDAxMjA1MzI4LEhOMDEyMDAwNDgzNyxZLFksTixBLFIwMDAxMiwwMTIwNTMzNSxITjAxMjAwMDQ4MzcsWSxZLE4sQSxSJw==';
$str = base64_decode($str);
var_dump(strpos($str, "\n"));