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empty
(PHP 4, PHP 5, PHP 7)
empty — Determine whether a variable is empty
Description
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)
NULLFALSE- array() (an empty array)
Changelog
| Version | Description |
|---|---|
| 5.5.0 |
empty() now supports expressions, rather than only variables. |
| 5.4.0 |
Checking non-numeric offsets of strings returns |
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 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
- isset() - Determine if a variable is declared and is different than NULL
- __isset()
- unset() - Unset a given variable
- array_key_exists() - Checks if the given key or index exists in the array
- count() - Count all elements in an array, or something in an object
- strlen() - Get string length
- The type comparison tables
English translation
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Document created the 30/01/2003, last modified the 26/10/2018
Source of the printed document:https://www.gaudry.be/en/php-rf-empty.html/.html/.html
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References
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