Question 1

What is a storage class in C programming?

Accepted Answer

A storage class in C defines the scope, lifetime, and visibility of variables and functions. It specifies where a variable is stored, how long it stays in memory, and how it is accessible within the program.

Question 2

What are the different types of storage classes in C?

Accepted Answer

C has four primary storage classes:
auto: Local variables with automatic duration.
register: Variables stored in CPU registers for faster access.
static: Variables retain their value across function calls and have a lifetime throughout the program execution.
extern: Used for global variables shared across multiple files.

Question 3

What is the default storage class for local variables?

Accepted Answer

The default storage class for local variables is auto. You don’t need to specify it explicitly as local variables are treated as auto by default.

Question 4

What is the difference between auto and static storage classes?

Accepted Answer

auto variables are destroyed once the function or block where they are declared finishes execution. They do not retain their value between function calls.
static variables retain their value between function calls and are initialized only once. Their lifetime extends across the entire program execution.

Question 5

Can we explicitly declare a variable as auto?

Accepted Answer

Yes, you can explicitly declare a variable as auto, but it’s rarely done since auto is the default storage class for local variables.

Question 6

What is the purpose of the register storage class?

Accepted Answer

The register storage class hints the compiler to store the variable in a CPU register instead of RAM for faster access. It is typically used for loop counters or frequently accessed variables, but modern compilers handle such optimizations automatically.

Question 7

How does static affect the scope of global variables?

Accepted Answer

When a global variable is declared as static, its scope is limited to the file in which it is declared. This means it cannot be accessed by other files in the program, making it file-specific.

Question 8

What is the difference between extern and static in terms of global variables?

Accepted Answer

extern allows a global variable to be accessed across multiple files.
static limits the scope of a global variable to the file where it is declared.

Question 9

Can we use extern for local variables?

Accepted Answer

No, the extern keyword is used only for global variables and functions. It cannot be applied to local variables.

Question 10

What is the scope of an extern variable?

Accepted Answer

The scope of an extern variable is global, meaning it can be accessed across multiple files in the program where it is declared.

Question 11

Can we modify the value of an extern variable in another file?

Accepted Answer

Yes, you can modify the value of an extern variable in any file where it is declared using the extern keyword, provided it is defined in one of the files.

Question 12

When should I use the static keyword for functions?

Accepted Answer

The static keyword can be applied to functions to limit their visibility to the file in which they are defined. This means the function cannot be accessed from other files, providing better encapsulation.

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