- var_dump: documentation ( source)
- filter_var: documentation ( source)
<?php
echo 'boolean filter:' . PHP_EOL;
$on = filter_var('on', FILTER_VALIDATE_BOOLEAN);
$true = filter_var('true', FILTER_VALIDATE_BOOLEAN);
$one = filter_var('1', FILTER_VALIDATE_BOOLEAN);
var_dump($on, $true, $one, $ON);
$false = filter_var('everythingElse', FILTER_VALIDATE_BOOLEAN);
var_dump($false);