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# empty

(PHP 3, PHP 4 )

empty -- Determine whether a variable is set

## Description

boolean empty ( mixed var)

> Note: empty() is a language construct.

This 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.

    $var = 0;

    if (empty($var)) {  // evaluates true
        echo '$var is either 0 or not set at all';
    }

    if (!isset($var)) { // evaluates false
        echo '$var is not set at all';
    }

Note that this is meaningless when used on anything which isn't a variable; i.e. empty (addslashes ($name)) has no meaning since it would be checking whether something which isn't a variable is a variable with a `FALSE` value.

See also isset() and unset().

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