- strstr: documentation ( source)
- implode: documentation ( source)
- str_replace: documentation ( source)
<?php
$out = "";
$arr = array();
$test = array('checkbox_1' => true);
foreach( $test as $name => $element) {
if(strstr($name, 'checkbox') !== false)
$arr[] = str_replace('_', '', strstr($name, 'checkbox'));
}
$out = implode(',', $arr);
echo $out;