3v4l.org

run code in 300+ PHP versions simultaneously
<?php $str = 'a\\\\,b,c\\,d'; print_r(preg_split('/(?<![^\\\\][\\\\]),/', $str)); print_r(preg_split('/(?<!(?<!\\\\)\\\\),/', $str)); print_r(preg_split('/(?<![^\\\\])(?<!\\\\),/', $str));

preferences:
37.33 ms | 402 KiB | 5 Q