- var_dump: documentation ( source)
- in_array: documentation ( source)
<?php
var_dump(in_array("foo", array(0)));
var_dump(in_array("foo", array('')));
var_dump(in_array("foo", array(false)));
var_dump(in_array("foo", array(null)));
var_dump(in_array("foo", array(1)));
var_dump(in_array("foo", array(0), true));