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C Storage Classes Interview Questions
36. Define storage classes and what are the different types of storage classes in C?
A storage class defines the scope, visibility and life-time of variables. Refer For More C Storage Classes
- auto storage class
- static storage class
- register storage class
- extern storage class
37. Define auto storage class?
- All variables declared inside a function without any storage classes keyword is considered as auto storage class by default.
- In auto storage class a memory is allocated automatically to the variables when the function is called and deallocates automatically when the function exits.
- Variables under auto storage classes are local to the block or function. So, it is also called as local variables.
- The keyword auto is rarely used because all uninitialized variables are said to have auto storage classes.
Refer For More C Auto Storage Classes
38. Define static storage class?
- A static variable is a variable that tells the compiler to retain the value until the program terminates.
- They are created once when the function is called, even though the function gets repeated it retains the same value and exists until the program terminates.
- The default value of static variable is zero(0).
- The keyword for a variable to declared under static storage class is static
Refer For More C Static Storage Classes
39. Define register storage class?
- Register variables are similar to auto variables. The only difference is register variables are stored in CPU register instead of memory.
- Register variables are faster than normal variables. Mostly programmers uses register to store frequently used variables.
- Programmers can store only few variables in the CPU register because size of register is less.
- The keyword for a variable to declared under register storage class is register.
Refer For More C Register Storage Classes
40. Define extern storage class?
- extern variable is a programmer's shorthand to represent external variable.
- extern variables are also known as global variables because extern variables are declared above the main function.
- So, the variables can be accessed by any function.
- We can also access extern variables of one file to another file. But make sure both files are in same folder. The keyword for a variable to declared under extern storage class is extern.
Refer For More C Extern Storage Classes
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