3v4l.org

run code in 300+ PHP versions simultaneously
<?php $recipients = [ "kumar", "ram@test.com", "ravi", "rob@example.com" ]; echo implode( ', ', preg_replace( '/^[^@]+$/', '$0@test.com', $recipients ) );
Output for 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.26, 8.4.1 - 8.4.13
kumar@test.com, ram@test.com, ravi@test.com, rob@example.com

preferences:
68.93 ms | 406 KiB | 5 Q