Five forms of variable storage

Five forms of variable storage

• From c++ Prime Plus P310

	Persistent	Scope	Linkability	How to declare
automatic	automatic	Code block	no	In the code block
register	automatic	Code block	no	In the code block, use the keyword register
Static, no linkability	Static	Code block	no	In the code block, use the keyword static
Static, external linkability	Static	file	External	Not in any function
Static, internal linkability	Static	file	internal	No longer go to any function, use the keyword static

• The object declared by const is the local variable of the file by default. This variable can only be in that file and cannot be accessed by other files. By specifying the const variable as extern, you can access this variable in the entire program
• By default, the linkability of the function is external, which can be shared between files, and the keyword static can be used to set the linkability of the function to internal so that it can only be used in one file