Storage Class and Scope

Scope

• Global to the Entire Application
• Local to the Source File
• Local to Function/Block

Storage Class

• Static
• Automatic

Declaration vs Definition

• Declaration: Specifies the type of the object. All objects must be declared before being used.
• Definition: Reserves storage for the object. May only define each object ONCE.

		Scope
		Global Object Lexical Scope		Local Object Lexical Scope
Storage Class	Uninitialized Value	Global to Entire Application	Local to Source File	Local to Block
Static	Set to 0	/* static and global declared */ extern int var; /* static and global defined */ int var;	/* static and local to a file */ static int var;	/* static and local */ void func(void) { static int var; }
Automatic	UNDEFINED			/* automatic and local */ void func(void) { int var; }

Other Lexical Scopes

• Struct, Union, and Enum types and Typedefs
• Struct and Union members