If you’re here, it’s probably because you’ve come across an error like this in your PHP Application.
Notice: Undefined variable: variable_name in /index.php on line 3
The reason this type of thing happens is because you are attempting to use a variable before you have defined it. If you were to run the code example below, you would see a similar error occur.
<?php echo $variable_name; $variable_name = 'Variable Name';
You will see that
$variable_name is not defined until after you actually use it.