3v4l.org

run code in 300+ PHP versions simultaneously
<?php $strings = [ 'my_name_is_John_Doe', 'my_name_is john doe', 'my_name_is_john_doe', 'i_am_20_years_old', "i'm_cool!" ]; foreach ($strings as $string) { echo json_encode([ $string, !strlen(ltrim($string, 'a..z_')), !preg_match('/[a-z_]*[^a-z_]/', $string) ]); echo "\n\n"; }
Output for 7.4.0 - 7.4.33, 8.0.1 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.27, 8.4.1 - 8.4.14
["my_name_is_John_Doe",false,false] ["my_name_is john doe",false,false] ["my_name_is_john_doe",true,true] ["i_am_20_years_old",false,false] ["i'm_cool!",false,false]
preferences:
143.88 ms | 407 KiB | 5 Q