How-to articles, tricks, and solutions about ISSET
Best way to test for a variable's existence in PHP; isset() is clearly broken
In PHP, the isset() function is used to check if a variable has been set, meaning that it has been declared and is not equal to NULL.
How to Read Whether a Checkbox is Checked in PHP
In this tutorial, you can find comprehensive information on how to read whether a checkbox is checked in PHP.
isset PHP isset($_GET['something']) ? $_GET['something'] : ''
In PHP, isset() is a function that determines whether a variable is set and is not NULL.