3v4l.org

run code in 300+ PHP versions simultaneously
<?php $s='<?php $s=4; echo str_replace(2+2,chr(39).$s.chr(39),$s); ?>'; echo str_replace(2+2,chr(39).$s.chr(39),$s); ?>

preferences:
48.08 ms | 402 KiB | 5 Q