Variable to be checked
Note: empty() only checks variables as anything else will result in a parse error. In other words, the following will not work: empty(trim($name)).
empty() is the opposite of (boolean) var, except that no warning is generated when the variable is not set.
Returns FALSE if var has a non-empty and non-zero value.
The following things are considered to be empty:
|"" (an empty string)|
|0 (0 as an integer)|
|"0" (0 as a string)|
|array() (an empty array)|
|var $var; (a variable declared, but without a value in a class)|
Example 1. A simple empty() / isset() comparison.
Note: Because this is a language construct and not a function, it cannot be called using variable functions