Variable handling Functions
PHP Manual

empty

Determine whether a variable is empty

Description

bool empty(mixed $var)

Determine whether a variable is considered to be empty. A variable is considered empty if it does not exist or if its value equals false. empty does not generate a warning if the variable does not exist.

Parameters

var

Variable to be checked

No warning is generated if the variable does not exist. That means empty is essentially the concise equivalent to !isset($var) || $var == false. This also applies to nested structures, such as a multidimensional array or chained properties.

Return Values

Returns true if var does not exist or has a value that is empty or equal to zero, aka falsey, see conversion to boolean. Otherwise returns false.

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';
}
?>

Example #2 empty on String Offsets

<?php
$expected_array_got_string = 'somestring';
var_dump(empty($expected_array_got_string['some_key']));
var_dump(empty($expected_array_got_string[0]));
var_dump(empty($expected_array_got_string['0']));
var_dump(empty($expected_array_got_string['0.5']));
var_dump(empty($expected_array_got_string['0 Mostel']));
?>

The above example will output:

bool(true)
bool(false)
bool(false)
bool(true)
bool(true)

Example #3 empty on multidimensional arrays

<?php
$multidimensional = [
    'some' => [
        'deep' => [
            'nested' => 'value'
        ]
    ]
];

if (!empty($multidimensional['some']['some']['nested'])) {
    $someVariable = $multidimensional['some']['deep']['nested'];
}

var_dump(empty($multidimensional['some-undefined-key']));
var_dump(empty($multidimensional['some']['deep']['unknown']));
var_dump(empty($multidimensional['some']['deep']['nested']));
?>

The above example will output:

bool(true)
bool(true)
bool(false)

Notes

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

Note:

When using empty on inaccessible object properties, the __isset() overloading method will be called, if declared.

See Also