3v4l.org

run code in 300+ PHP versions simultaneously
<?php $string = 'REGISTER 11223344 here'; var_export( preg_replace('/(?<=REGISTER )(.*)(?= here)/','',$string) );
Output for 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.26, 8.0.0 - 8.0.13, 8.1rc1 - rc3
'REGISTER here'

preferences:
41.54 ms | 460 KiB | 5 Q