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<?php $first = "."; $last = "a"; $middle= "testing-123.test"; echo "First segment:\t" . (ctype_alnum($first) ? 'valid' : 'invalid') . "\n"; echo "Second segment:\t" . (preg_match("/^[a-z\d.-]+$/i", $middle) ? 'valid' : 'invalid') . "\n"; echo "Third segment:\t" . (ctype_alnum($last) ? 'valid' : 'invalid');

preferences:
25.73 ms | 405 KiB | 5 Q