3v4l.org

run code in 500+ PHP versions simultaneously
<?php define('MYERROR', -1); function &f1() {return -1;} function &f2() {return MYERROR;} $v = f1(); $v = 2; var_dump($v); $v = f2(); $v = 2; var_dump($v);

preferences:
108.66 ms | 2078 KiB | 5 Q