What does var mean in php

var means variable variable in PHP; in PHP, class attributes must be defined as one of public, protected, and private. If defined with var, they are considered public.

The operating environment of this article: Windows 7 system, PHP version 7.1, DELL G3 computer

What does var mean in php?

The defined string variable name

var represents the meaning of variable variable

Usage of var keyword in php

I see many friends saying that it doesn’t matter whether you use var or not when defining variables in php, but that’s not the case.

Look at the example, if I use var like this:

 var $a=123;
 echo $a;
 //那么程序会提示语法错误，要去掉var这个变量定义才行。直接
 $a=123;
 echo $a;
 //这样才不会报错，php是弱类型语言，所以不声明类型是没问题的。

When can var be used? Please see:

 class Test{
 var $a=123;//访问控制，这里的var不用就不正常，当然你可以用public protected等关键词代替，来声明成员变量的属性
 
 }
 $obj=new Test();
 echo $obj->a;
 //打印结果：123

If you replace var with public, it will work.

But at this time, if you remove var in the class and there is no access modifier, it will prompt a syntax error.

In fact, after testing, I believe that var is an alias for public and is used to define public properties in a class. However, due to historical issues, var is no longer used now. Later, I checked the php official website and it turned out to be true.

php official explanation:

Class attributes must be defined as one of public, protected, and private. If defined with var, it is considered public.

Note: For compatibility reasons, the method of defining variables using the var keyword in PHP 4 is still valid in PHP 5 (just as an alias for the public keyword). In versions before PHP 5.1.3, this syntax will generate an E_STRICT warning

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