Explanation of Global keyword reference in PHP Global variables

$ GLOBALS reference to the PHP manual:

Global variable: $ GLOBALS
Note: $ GLOBALS is applicable to PHP 3.0.0 and later versions.

An array composed of all defined global variables. The variable name is the index of the array.

This is a "superglobal", or it can be described as an automatic global variable.
That is to say, $ var1 and $ GLOBALS ['var1'] in the above code refer to the same variable, rather than two different variables!

Examples of global variables

The code is as follows:	Copy code
<? Php $ Pangbu = "pangbu ";   Function demo (){   Global $ pangbu;   Echo $ pangbu;  }   Demo (); ?>

Explanation

In fact, global $ pangbu; is short for $ pangbu = & $ _ GLOBAL ['pangbu,

$ Pangbu is a reference of $ _ GLOBAL ['pangbu ']. As for how to use the reference, $ pangbu is used.
Some of your own notes
I have never understood the usage of global before. Although I can use it, I have been confused in Zookeeper. Now I finally understand it.
.

For more information about Global applications, see the following php case:

The code is as follows:	Copy code
<? Php $ Url = "www.111cn.net "; Function get_url (){ Echo "The blog is". $ url; // $ url is not obtained here, because it is just an undefined local variable.     } Get_url (); ?>

 
The above example will report a notice error!

The code is as follows:	Copy code
<? Php $ Url = "www.111cn.net "; Function get_url (){ Global $ url; Echo "The blog url is". $ url;  } Get_url (); ?>

 
The above usage is correct. After the global variable is declared in the function, all referenced variables of any variable will point to the global variable!

It is also worth mentioning that the global array $ GLOBALS [] is rewritten as follows in the above example:

The code is as follows:	Copy code
<? Php $ Url = "www.111cn.net "; Function get_url (){ Echo "The blog url is". $ GLOBALS ['URL'];  } Get_url (); ?>

Note that global declared variables cannot be copied, such as global $ url = "www.111cn.net". This is incorrect.