empty

(PHP 4, PHP 5, PHP 7)

emptyDetermine whether a variable is empty


Description

empty ( mixed $var ) : bool

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

Note:

Prior to PHP 5.5, empty() only supports variables; anything else will result in a parse error. In other words, the following will not work: empty(trim($name)). Instead, use trim($name) == false.

No warning is generated if the variable does not exist. That means empty() is essentially the concise equivalent to !isset($var) || $var == false.


Return Values

Returns FALSE if var exists and has a non-empty, non-zero value. Otherwise returns TRUE.

The following values are considered to be empty:

  • "" (an empty string)
  • 0 (0 as an integer)
  • 0.0 (0 as a float)
  • "0" (0 as a string)
  • NULL
  • FALSE
  • array() (an empty array)


Examples

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

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

Example #2 empty() on String Offsets

PHP 5.4 changes how empty() behaves when passed 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['0.5']));var_dump(empty($expected_array_got_string['0 Mostel']));?>

Output of the above example in PHP 5.3:


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

Output of the above example in PHP 5.4:


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

Notes

Note:

Because this is a

language construct and not a function, it cannot be called using variable functions.

Note:

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

See Also