This question already has an answer here:
None of the solutions in the other threads were clear. I need help removed the undefined message. The line of code that is causing it is this variable:
$ain = $_Get['AIN'];
Other threads mentioned using upset although I could not follow. I want to be able to pass a value in whether it is null or not.
</div>
You have to check the existence of the array index before using it, and provide an alternative value to use in case it isn't set.
For example:
if(isset($_GET['AIN'])){
//The value is set and you can use it
$ain = $_GET['AIN'];
} else {
//The value is not set, so you should provide a default value
$ain = NULL;
}
Also note that the PHP language is case sensitive, so if you want to refer to HTTP GET parameters, you should use $_GET, because $_Get will not work.
Assuming you meant to reference the superglobal $_GET, you can use one of the following:
<?php
$ain = 'default';
if(isset($_GET['AIN']))
$ain = $_GET['AIN'];
Or use the ternary:
<?php
$ain = isset($_GET['AIN']) ? $_GET['AIN'] : 'default';
Or the shortest with the null-coalescing operator:
<?php
$ain = $_GET['AIN'] ?? 'default';