NetEase Cloud Classroom _c Language programming sixth week: Program Structure: Memory model (global variables and local variables), header files, macro definitions, function pointers and callback functions, the message mechanism of the ACL graphics library

6.1 Global Variables

6.2 Compilation preprocessing

6.3 Large Program Structure

6.1 Global Variables

Global variables

Variables defined outside the function are global variables

Global variables have global lifetimes and scopes

They have nothing to do with any function.

They can be used inside any function

Global variable Initialization

A global variable that does not initialize will get a value of 0

The pointer will get a null value

Global variables can only be initialized with values that are known at compile time

Their initialization occurs before the main function

Global variables that are hidden

If there is a variable with the same name as the global variable inside the function, the global variable is hidden

6.2 Compilation preprocessing

6.3 Large Program Structure

NetEase Cloud Classroom _c Language programming sixth week: Program Structure: Memory model (global variables and local variables), header files, macro definitions, function pointers and callback functions, the message mechanism of the ACL graphics library