<?php $username_pattern = '/^(?!\d*$)[a-z0-9]{8,20}$/'; $userNames = [ "1a3b5678", "1a3b5678abcd", "12345678", "1a3b5678abcddddddddddddddddddddddddddddddd", "1a3B5678", "a1" ]; foreach ($userNames as $userName) { if (preg_match($username_pattern, $userName)) { echo "Match - $userName" . PHP_EOL; } else { echo "No match - $userName" . PHP_EOL; } }
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