PHP empty function

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empty

(PHP 3, PHP 4, PHP 5)

Determine whether a variable is considered to be empty.

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:

As of PHP 5, objects with no properties are no longer considered empty.

As of PHP 4, The string value “0″ is considered empty.

Example 1.
A simple empty() / isset()
comparison.

$var = 0;
 
// Evaluates to true because $var is empty
if (empty($var)) {
    echo '$var is either 0, empty, or not set at all';
}
 
// Evaluates as true because $var is set
if (isset($var)) {
    echo '$var is set even though it is empty';
}

Note: Because this is a
language construct and not a function, it cannot be called using
variable functions