empty() returns FALSE if var has a non-empty and non-zero value. In other words, "", 0, "0", NULL, FALSE, array(), and var $var; are all considered empty. In PHP 4 and earlier, objects with empty properties are considered empty. This is not the case in PHP 5. TRUE is returned if var is empty.
empty() is the opposite of (boolean) var, except that no warning is generated when the variable is not set. See converting to boolean for more information.
Example 1. A simple empty() / isset() comparison.
Note: Because this is a language construct and not a function, it cannot be called using variable functions
Note: empty() only checks variables as anything else will result in a parse error. In other words, the following will not work: empty(addslashes($name)).