Global variables in PHP

1. you can use session_register to register global variables available throughout the session. For example, session_register ("name") registers a global variable $ name, which can be directly used on the PHP page, if you want to use $ name in a function, you must add global $ name.
2. Data submitted using the POST method can be accessed through the $ _ post array.
3. Data transmitted using the get method can be accessed through the $ _ Get array.
4. If the option register_globals in PHP. INI is set to on, the variables submitted by the post and get methods can be directly referenced without the 2 and 3 methods. This option is off by default for security reasons.