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<?php $dates = array('1-2018','5-2019','10-2018','5-2020','9-1978','6-2001'); usort($dates, function($a,$b){ return strtotime('1-'.$a) <=>strtotime('1-'.$b);}); var_export($dates); echo "\n"; echo "Min: ".reset($dates)."\n"; echo "Max: ".end($dates)."\n";
Output for 7.1.0 - 7.1.33, 7.2.0 - 7.2.34, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.30, 8.2.0 - 8.2.25, 8.3.0 - 8.3.13
array ( 0 => '9-1978', 1 => '6-2001', 2 => '1-2018', 3 => '10-2018', 4 => '5-2019', 5 => '5-2020', ) Min: 9-1978 Max: 5-2020

preferences:
81.91 ms | 407 KiB | 5 Q