Differences between static and global

1. global takes effect on the entire page.
2. static only works in function and class.
The usage of global and $ GLOBALS is basically the same, but they are mostly different in actual development.
Global generates an alias variable pointing to the external variable of the function, instead of the real external variable of the function. Once the pointing address of the alias variable is changed, unexpected situations may occur, example 1.
$ GLOBALS [] is actually called as an external variable, and the internal and external functions will always be consistent!