PHP: empty - Manual

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)

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'; } ?>

User Contributed Notes
empty

myfirstname dot barros at gmail dot com
29-Apr-2005 10:15


<?php

$a = Array( ); #<- empty

$a = Array( '' ); #<- NOT empty

$a = Array( Null ); #<- NOT empty

?>



---

gabriel

rehfeld.us
23-Aug-2004 03:47


ive found the empty() contruct extremely usefull. For some reason people seem to think its of little use, but thats not so.



for example, form fields can be checked in 1 step by using empty(). (assuming a basic check of whether it was submitted and if submitted, that it was not empty.)



<?php



if (!empty($_POST['name'])) $name = $_POST['name'];



?>



compared to isSet(), this saves an extra step. using !empty() will check if the variable is not empty, and if the variable doesnt exit, no warning is generated.



with isSet(), to acheive the same result as the snippit above, you would need to do this:



<?php



if (isSet($_POST['name']) && $_POST['name']) $name = $_POST['name'];



?>



so using !empty() reduces code clutter and improves readability, which IMO, makes this VERY usefull.

paul at worldwithoutwalls dot co dot uk
22-May-2004 12:09


Note the exceptions when it comes to decimal numbers:



<?php

$a = 0.00;

$b = '0.00';

echo (empty($a)? "empty": "not empty"); //result empty

echo (empty($b)? "empty": "not empty"); //result not empty

//BUT...

$c = intval($b);

echo (empty($c)? "empty": "not empty"); //result empty

?>



For those of you using MySQL, if you have a table with a column of decimal type, when you do a SELECT, your data will be returned as a string, so you'll need to do apply intval() before testing for empty.



e.g.

TABLE t has columns id MEDIUMINT and d DECIMAL(4,2)

and contains 1 row where id=1, d=0.00

<?php

$q = "SELECT * FROM t";

$res = mysql_query($q);

$row = mysql_fetch_assoc($res);

echo (empty($row['d'])? "empty": "not empty"); //result not empty

?>

phpcheatsheet at blueshoes dot org
27-Nov-2002 01:18


the php cheatsheet gives a good overview for empty(), isSet(), is_null() etc. http://www.blueshoes.org/en/developer/php_cheat_sheet/



to chris at chaska dot com:

that line

if ( ! isset( $var ) ) return TRUE;

won't do anything, it's useless in that scope.

empty

Description

Parameters

Return Values

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Examples

Notes

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