3v4l.org

run code in 300+ PHP versions simultaneously
<?php $str = "Hello, How Are You."; echo preg_replace( '/\b([a-z])([a-z])/i', '$2$1', $str );
Output for 8.0.1 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.19, 8.3.0 - 8.3.7
eHllo, oHw rAe oYu.

preferences:
98.1 ms | 402 KiB | 91 Q