What is the utility of storage class in c?

Answer 1

In C there are four storage classes: auto, static, extern and register. These storage classes essentially define the scope or visibility of a name (a function or variable). All four are inherited from B, the language from which C evolved.

• The auto storage class is used to explicitly declare a non-static local variable. However, given that all non-static local variables are implicitly automatic in C, explicit use of the auto storage class is therefore redundant in C. Moreover, in C++11, explicit use of the auto storage class was dropped entirely; the auto keyword is now used for automatic type deduction in C++.
• The static storage class is used to explicitly declare a static local variable. In addition, all global variables and functions are implicitly static and have external linkage, but if explicitly declared static they have internal linkage only.
• The extern storage class is used to allow access to a name that has external linkage.
• The register storage class is used to define a variable that should be allocated in a CPU register rather than in working memory (RAM).