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<?php $res = array(); $btn = "17/08/2014"; preg_match("/^(0[1-9]|[1-2][0-9]|3[0-1])\/(0[1-9]|1[0-2])\/[0-9]{4}$/",$btn,$res); var_dump($res);
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.7 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.10, 7.2.0 - 7.2.33, 7.3.12 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.7
array(3) { [0]=> string(10) "17/08/2014" [1]=> string(2) "17" [2]=> string(2) "08" }

preferences:
218.34 ms | 406 KiB | 315 Q