A storage class specifier is used to refine the declaration
of a variable, a function, and parameters. Storage classes determine
whether:
- The object has internal, external, or no linkage
- The object is to be stored in memory or in a register, if available
- The object receives the default initial value of 0 or an indeterminate default initial value
- The object can be referenced throughout a program or only within the function, block, or source file where the variable is defined
- The storage duration for the object is maintained throughout program run time or only during the execution of the block where the object is defined
For a variable, its default storage duration, scope, and
linkage depend on where it is declared: whether inside or outside
a block statement or the body of a function. When these defaults are
not satisfactory, you can use a storage class specifier to explicitly
set its storage class. The storage class specifiers are:
- auto
- static
- extern
- register
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