- var_dump: documentation ( source)
- array_keys: documentation ( source)
- range: documentation ( source)
<?php
$show = array(
'mon' => false,
'tue' => false,
'wed' => false,
'thu' => false,
'fri' => false,
'sat' => false,
'sun' => false
);
$keys = array_keys($show);
foreach (range(0,6) as $index) {
$key = $keys[$index];
$show[$index] |= true; // in your case |= isset($post[$index]);
}
var_dump($show);