- preg_match_all: documentation ( source)
<?php
$app_filename = "AntivirusSecurity_02_cb-508164-ce_ac8a0e5e-35f8-4c7b-b591-7e28cab94b4e.apk";
$app_filename = "AntivirusSecurity_02_[508164]_ac8a0e5e-35f8-4c7b-b591-7e28cab94b4e.apk";
$click_id_fence_beginning = '\[';
$click_id_fence_end = '\]';
preg_match_all("^{$click_id_fence_beginning}(.*?){$click_id_fence_end}^",$app_filename,$fields, PREG_PATTERN_ORDER);
echo $fields[1];
//print_r($fields);