empty
]Podporované v PHP 4, PHP 5
Syntax
bool empty ( mixed $var )
Popis
Príkaz jazyka
PHP
Determine whether a variable is considered to be empty.
Parameters
var - Variable to be checked
Note: empty() only checks variables as anything else will result in a parse error. In other words, the following will not work: empty(
trim
($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
Version
Description
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.
Príklad
<?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'
;
}
?>
Pozri aj
isset
,
unset
,
array_key_exists
,
count
,
strlen
]