What is the use of isset() in PHP?

isset() checks whether a variable is set and is not NULL. It returns true if the variable exists and has a value, otherwise false.

<?php
$name = "Robin";

var_dump(isset($name));
var_dump(isset($age));
?>

Output:

It is mostly used with forms, for example isset($_POST["email"]), to avoid “undefined index” warnings. Read the full chapter PHP isset() function, and learn the difference with empty().

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