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 PHP manuál : function.empty.html

empty
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empty

(PHP 3, PHP 4, PHP 5 )

empty -- Determine whether a variable is empty

Description

bool empty ( mixed var )

Determine whether a variable is considered to be empty.

Parameters

var

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.

Return Values

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)
NULL
FALSE
array() (an empty array)
var $var; (a variable declared, but without a value in a class)

ChangeLog

VersionDescription
PHP 5

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

PHP 4

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

Examples

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';
}
?>

Notes

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

See Also

isset()
unset()
array_key_exists()
count()
strlen()
The type comparison tables

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