Hey there fellow developers,
I've been working on a PHP project and I came across a situation where I need to check if a variable is set or not. Now, I'm a little confused about which approach to use: isset or is not set. I understand that both can be used to achieve the same result, but I'm not sure which one would be the best practice or more appropriate in this scenario.
To provide some context, let me explain the specific situation I'm dealing with. I have a form where users can enter some data, and I'm storing that data in variables to be used later on. However, not all form fields are required, so some variables might not be set depending on what the user fills out.
In my case, I want to check if a specific variable has been set before using it further down in my code. But I want to do it in a way that is considered best practice and follows the PHP coding standards.
So, my question is: should I use isset or is not set to check if a variable is set or not? And which one would be recommended in this scenario? I would really appreciate it if someone could shed some light on this confusion and provide some guidance.
Thanks in advance for your help!

Hey there,
In my personal experience, when it comes to checking if a variable is set or not in PHP, I usually prefer using `isset()`. The `isset()` function is specifically designed for this purpose and it returns true if the variable exists and has a non-null value.
One advantage of using `isset()` is that it can check multiple variables at once, making it quite handy when you have a lot of variables to validate. Additionally, `isset()` is a language construct, so it has better performance compared to other approaches like `is not set`.
Another benefit of using `isset()` is that it won't throw a notice if the variable doesn't exist. This is particularly useful when you're dealing with user input or external data, where certain fields may or may not be present.
However, please keep in mind that if you use `isset()` on an array element that has a `null` value, it will return false. So, if you anticipate the possibility of having `null` values, you might need to handle that separately.
Overall, in my opinion, `isset()` is a reliable and widely used method for checking variable existence in PHP. It keeps the code clean and readable while efficiently handling the checking operation. Hope this helps!