Question
What are the different between isset(), !empty(), !is_null() ?
Those are three functions allow you to determine the nature of a variable, with a bit different.
Comparison table
| $value | gettype($value) | isset($value) | !empty($value) | !is_null($value) |
|---|---|---|---|---|
| 0 | integer | TRUE | - | TRUE |
| NULL | NULL | - | - | - |
| FALSE | boolean | TRUE | - | TRUE |
| $undefined | NULL | - | - | - |
| "" | string | TRUE | - | TRUE |
| TRUE | boolean | TRUE | TRUE | TRUE |
| 1 | integer | TRUE | TRUE | TRUE |
| "TXT" | string | TRUE | TRUE | TRUE |
More details : http://php.net/manual/en/types.comparisons.php
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