- var_dump: documentation ( source)
<?php
var_dump("0" == "checked");
var_dump(0 == "checked");
var_dump("0" === "checked");
var_dump(0 === "checked");
var_dump("checked" == "0");
var_dump("checked" == 0);
var_dump("checked" === "0");
var_dump("checked" === 0);