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empty

(PHP 3, PHP 4, PHP 5 )

empty -- Determine whether a variable is empty

Description

bool empty ( mixed var)

empty() returns FALSE if var has a non-empty and non-zero value. In otherwords, "", 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.

<?php
$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

Note: empty() only checks variables as anything else will result in a parse error. In otherwords, the following will not work: empty(addslashes($name)).

See also isset(), unset(), array_key_exists(), count(), strlen(), and the type comparison tables.

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