<html>
<body>
$a = 0;
// True because $a is set
if (isset($a)) {
echo "Variable 'a' is set.<br>";
}
$b = null;
// False because $b is NULL
if (isset($b)) {
echo "Variable 'b' is set.";
}
</body>
<!-- Mirrored from www.w3schools.com/php/phptryit.asp?filename=tryphp_func_var_isset by HTTrack Website Copier/3.x [XR&CO'2014], Mon, 27 Jan 2020 02:51:08 GMT -->
</html>