- str_replace: documentation ( source)
- error_reporting: documentation ( source)
- array_unique: documentation ( source)
- str_split: documentation ( source)
<?php
error_reporting(0);
$a = "abcdefffefa";
for($i = 0; $i < 30; $i++) $a = $a . $a;
$b = "afe";
print(str_replace(array_unique(str_split($b)), "", $a));