Define and Access array in constants PHP

PHP 5.5 and in older version constants cannot store directly array

In this matter we are allowing to upload limited file’s extensions and this is not good codding practice to defined allowed extensions and check every file on uploading code because we needs to store allowed extensions in a single place for easily modify them.

Code of store and get array from constant

Through a trick define array and convert into a json string with json_encode function

define('allow_ext',json_encode(array('jpeg','jpg','png','mp4','txt','doc','xls')));

Get stored array data from constant

Here is contacts allow_ext will return json string and then convert it into array with json_decode function

$allow_ext = json_decode(allow_ext,true);

PHP 5.6+ easily store and access array data from constant

const allow_ext = ['jpeg','jpg','png','mp4','txt','doc','xls'];