3v4l.org

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<?php $pattern = '~ (?<animal>) (?<color>) ^ (?<animal>DOG|CAT)? (?<color>RED|BLUE)? $ ~xiJ'; if ( preg_match($pattern, 'dog', $m) ) print_r(array_filter($m, 'is_string', ARRAY_FILTER_USE_KEY));
Output for 7.4.0 - 7.4.33, 8.0.1 - 8.0.30, 8.1.0 - 8.1.34, 8.2.0 - 8.2.30, 8.3.0 - 8.3.30, 8.4.1 - 8.4.18, 8.5.0 - 8.5.3
Array ( [animal] => dog [color] => )
preferences:
102.22 ms | 1247 KiB | 4 Q