Test _php techniques for parsing empty is_null and isset in PHP

The code is as follows:

Copy Code code as follows:

<?php
$a;
$b = false;
$c = ';
$d = 0;
$e = null;
$f = Array ();

The first is empty's var_dump output:
Boolean true
Boolean true
Boolean true
Boolean true
Boolean true
Boolean true

Then the output of the Is_null:
Boolean true
Boolean false
Boolean false
Boolean false
Boolean true
Boolean false

Finally, the output of the isset:
Boolean false
Boolean true
Boolean true
Boolean true
Boolean false
Boolean true
This shows that empty () can be used to determine whether all data types are empty or false, and that Is_null is essentially the same as isset and can only be used to determine whether it is null and undefined.