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CHAPTER 3 DECLARATION OF TYPES AND STORAGE CLASSES

User’s Manual U15556EJ1V0UM

3.1 Storage Class Specifiers

A storage class specifier specifies the storage class of an object. It indicates the storage location of a value that

the object has, and the scope of the object. In a declaration, only one storage class specifier can be described. The

following five storage class specifiers are available.

• typedef

• extern

• static

• auto

• register

(1) typedef

The typedef specifier declares a synonym for the specified type.

See 3.6 below for details of the typedef

specifier.

(2) extern

The extern specifier indicates (tells the compiler) that the variable immediately before this specifier is declared

elsewhere in the program (i.e., an external variable).

(3) static

The static specifier indicates that an object has static storage duration. For an object that has static storage

duration, an area is reserved before the program execution and the value to be stored is initialized only once.

The object exists throughout the execution of the entire program and retains the value last stored in it.

(4) auto

The auto specifier indicates that an object has automatic storage duration. For an object that has automatic

storage duration, an area is reserved when the object enters a block to be declared.

At entry into the declared block from its top, the object is initialized if so specified. If the object enters the block

by jumping to a label within the block, the object will not be initialized.

The area reserved for an object that has automatic storage duration will not be guaranteed after the execution of

the declared block.

(5) register

The register specifier indicates that an object is assigned to a register of the CPU. With this C compiler, it is

allocated to the register or saddr area of the CPU. See CHAPTER 11 EXTENDED FUNCTIONS for details of

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