Home > php教程 > php手册 > 一张表搞清楚php is_null、empty、isset的区别,is_nullisset

一张表搞清楚php is_null、empty、isset的区别,is_nullisset

WBOY
Release: 2016-06-13 08:58:30
Original
860 people have browsed it

一张表搞清楚php is_null、empty、isset的区别,is_nullisset

isset 判断变量是否已存在

empty 判断变量是否为空或为0

is_null 判断变量是否为NULL

变量 empty is_null isset
$a=”” true false true
$a=null true true false
var $a true true false
$a=array() true false true
$a=false true false true
$a=15 false false true
$a=1 false false true
$a=0 true false true
$a=”0” true false true
$a=”true” false false true
$a=”false” false false true
Related labels:
source:php.cn
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Popular Recommendations
Popular Tutorials
More>
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template