In this new post to his blog, Brian Moon compares two things that, on the outside, might seem a lot alike but do have their differences under the hood - a null value and the isset function.

I am working with a newcomer to PHP and he asked me about setting a variable to null and how to check that. He had found some example or information that showed that setting a varaible equal to null would unset the variable. So, he was unclear if he could then reliably check if the variable was equal to null. Having avoided null like the plague in my years of PHP, I was not sure. So, I mocked up a quick script to see what the states of a variable are in relation to null.

His test verified that a variable, set equal to null will be found to be equal to null, will be set (isset) and will be found empty by PHP's empty