(PHP 4, PHP 5, PHP 7)
empty — 锟斤拷锟揭伙拷锟斤拷锟斤拷锟斤拷欠锟轿拷锟�
锟叫讹拷一锟斤拷锟斤拷锟斤拷锟角凤拷锟斤拷为锟角空的★拷锟斤拷一锟斤拷锟斤拷锟斤拷锟斤拷锟斤拷锟斤拷锟节ｏ拷锟斤拷锟斤拷锟斤拷锟斤拷值锟斤拷同锟斤拷FALSE锟斤拷锟斤拷么锟斤拷锟结被锟斤拷为锟斤拷锟斤拷锟节★拷锟斤拷锟斤拷锟斤拷锟斤拷锟斤拷锟斤拷诘幕锟斤拷锟�empty()锟斤拷锟斤拷锟斤拷锟斤拷锟斤拷锟斤拷妗�
var锟斤拷锟斤拷锟侥憋拷锟斤拷
Note:
锟斤拷 PHP 5.5 之前锟斤拷empty() 锟斤拷支锟街憋拷锟斤拷锟斤拷锟轿猴拷锟斤拷锟斤拷锟斤拷锟斤拷锟斤拷锟结导锟斤拷一锟斤拷锟斤拷锟斤拷锟斤拷锟襟。伙拷锟斤拷之锟斤拷锟斤拷锟叫达拷锟诫不锟斤拷锟斤拷效锟斤拷 empty(trim($name))锟斤拷 锟斤拷为锟斤拷锟斤拷锟接︼拷锟绞癸拷锟�trim($name) == false.
没锟叫撅拷锟斤拷锟斤拷锟斤拷锟斤拷锟斤拷锟铰憋拷锟斤拷锟斤拷锟斤拷锟斤拷锟节★拷 锟斤拷锟斤拷味锟斤拷 empty() 锟斤拷锟斤拷锟斤拷锟斤拷 !isset($var) || $var == false 锟饺价★拷
锟斤拷var锟斤拷锟节ｏ拷锟斤拷锟斤拷锟斤拷一锟斤拷锟角空凤拷锟斤拷锟街凳憋拷锟斤拷锟� FALSE
锟斤拷锟津返伙拷 TRUE.
锟斤拷锟铰的讹拷锟斤拷锟斤拷锟斤拷为锟角空的ｏ拷
NULLFALSE
| 锟芥本 | 说锟斤拷 |
|---|---|
| 5.5.0 |
empty() 锟斤拷锟斤拷支锟街憋拷锟绞斤拷耍锟斤拷锟斤拷锟斤拷锟斤拷锟斤拷潜锟斤拷锟斤拷锟� |
| 5.4.0 |
锟斤拷锟斤拷锟斤拷锟街碉拷锟街凤拷锟斤拷偏锟斤拷锟斤拷锟结返锟斤拷 |
Example #1 一锟斤拷锟津单碉拷 empty() 锟斤拷 isset() 锟侥比较★拷
<?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 锟斤拷锟街凤拷锟斤拷偏锟斤拷锟斤拷锟斤拷使锟斤拷empty()
PHP 5.4 锟睫革拷锟剿碉拷锟斤拷锟斤拷锟斤拷锟斤拷址锟斤拷锟狡拷锟斤拷锟绞憋拷锟� empty() 锟斤拷锟斤拷为
<?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']));
?>
锟斤拷锟斤拷锟斤拷锟斤拷锟斤拷PHP 5.3锟叫碉拷锟斤拷锟斤拷锟�
bool(false) bool(false) bool(false) bool(false) bool(false) bool(false)
锟斤拷锟斤拷锟斤拷锟斤拷锟斤拷PHP 5.4锟叫碉拷锟斤拷锟斤拷锟�
bool(true) bool(false) bool(false) bool(false) bool(true) bool(true)
Note: 锟斤拷为锟斤拷一锟斤拷锟斤拷锟皆癸拷锟斤拷锟斤拷锟斤拷锟斤拷锟斤拷一锟斤拷锟斤拷锟斤拷锟斤拷锟斤拷锟杰憋拷 锟缴变函锟斤拷 锟斤拷锟矫★拷
Note:
锟斤拷锟斤拷一锟斤拷锟斤拷锟缴硷拷锟侥讹拷锟斤拷锟斤拷锟斤拷使锟斤拷 empty() 时锟斤拷 __isset() 锟斤拷锟斤拷锟斤拷锟斤拷锟斤拷诘幕锟斤拷锟斤拷锟斤拷锟斤拷岜伙拷锟斤拷谩锟�