Storage class in C – free C programming tutorial

In this segment you will be familiarized with the storage class available for C programming langauge along with their syntax.

Storage class:

The storage location and scope or visibility of a variable or a function within a program is defined under storage classes in C.

There are four types of storage classes available in C , which are given as follows:

Automatic or Auto is a default storage-class for the basic variables and function (where a class does not mentioned before the variable )that we define or declare under a C program.
Hence the keyword auto is rarely used while writing a C program.
Auto variables or functions can be only accessed within the block/function in which they have been declared i.e. scope of auto variable is within the block of code.
They are assigned a garbage value by default whenever they are declared.
They get destroyed on exit from the block of code.

For example :

int count; or auto int count;

Both are similar as by default compiler takes the storage-class as auto for all variables and functions declared under a program.

In above example auto is a keyword which is used to indicate static variables.

Static type of variable is widely used in C programming language as static have a property to store the value of variable even if it is out its scope.
Static variable can not be accessed outside the program i.e. scope of auto variable is within the block of code but the maintain the value between two funtion calls.
Static variables have default value equal to zero and initialized only once in their lifetime.

For example :

static int count;

In above example static is a keyword which is used to indicate static variables.

Functionality of register class is same as the auto.
But the only difference is the values are stored directly into the registers of microprocessors i.e. they can be accessed directly.
They can be only accessed within the block/function in which they have been declared i.e. scope of auto variable is within the block of code.
They are assigned a garbage value by default whenever they are declared.
They get destroyed on exit from the block of code.

For example :

register int count;

In above example register is a keyword which is used to indicate static variables.

For example :

extern int count;

In above example extern is a keyword which is used to indicate static variables.

This is all about the storage class available for C programming tutorial along with their syntax.

If you have in doubt please comment below.