A table to clarify the difference between php is_null, empty and isset, is_nullisset_PHP tutorial

A table to clarify the difference between php is_null, empty and isset, is_nullisset

isset determines whether the variable already exists

empty determines whether the variable is empty or 0

is_null determines whether the variable is 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

http://www.bkjia.com/PHPjc/1028302.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/1028302.htmlTechArticleA table to clarify the difference between php is_null, empty and isset, is_nullisset isset determines whether the variable already exists empty determines the variable Whether it is empty or 0 is_null determines whether the variable is NULL variable...