Php variable null explanation

In php, we have many methods to determine whether variables are null. php provides functions such as empty, isset, varnull, and is_null for variable judgment, the following is a simple comparison of empty () and isset () using these methods:

In php, we have many methods to determine whether a variable is null. php provides functions such as empty, isset, var = null, is_null, and so on for variable judgment, next I will share with you how to use these methods. A simple comparison between empty () and isset.

The instance code is as follows: