Storage Class In C Language | Storage Class In C Language In Hindi

Storage Class In C

A storage class defines the scope (visibility) and life-time of variables and/or functions within a C Program. They precede the type that they modify. We have four different storage classes in a C program −

• auto
• register
• static
• extern

Fig: Storage class in c

The auto Storage Class

 

The auto storage class is the default storage class for all local variables.

Example:

{

int mount;

auto int mount;

}

Program

#include<stdio.h>

Int main()

{

auto int j=1;

{

auto int j=2;

{

auto int j=3;

printf(“%d”,j);

}

printf(“ \t %d”,j);

return 0;

}

Output:

3   2    1

 

The register Storage Class

The register storage class is used to define local variables that should be stored in a register instead of RAM. This means that the variable has a maximum size equal to the register size (usually one word) and can't have the unary '&' operator applied to it (as it does not have a memory location).

Example:

{

 register int   arr;

}

It should also be noted that defining 'register' does not mean that the variable will be stored in a register.

Program

#include<stdio.h>

main()

{

{ register int weight;

int *ptr=&weight;

}

}

 

Output:

Error:address of register variable ‘weight’ requested

 

The static Storage Class

The static storage class instructs the compiler to keep a local variable in existence during the life-time of the program instead of creating and destroying it each time it comes into and goes out of scope.

 It causes that variable's scope to be restricted to the file in which it is declared.

when static is used on a global variable, it causes only one copy of that member to be shared by all the objects of its class.

 

Example:

static int mount=10;

 

Program

#inlcude<stdio.h>

void next(void);

static int counter=7;

main()

{

While(counter<10)

next();

counter++;

return 0;

void next(void)

{

static int mount=13;

mount++;

printf(“mount=%d and counter=%d\n”,mount,counter);

}

 

Output:

 

Mount=14 and counter=7

Mount=15 and counter=8

Mount=16 and counter=9

 

The extern Storage Class

The extern storage class is used to give a reference of a global variable that is visible to ALL the program files. When you use 'extern', the variable cannot be initialized however, it points the variable name at a storage location that has been previously defined.

The extern modifier is most commonly used when there are two or more files sharing the same global variables or functions.

Example:

extern void display();

 

program

 

First file : main.c

 

#include<stdio.h>

extern i;

main()

{

printf(“value of the external integer is= %d\n”,i);

return 0;

}

 

 

Second file:support.c

#include<stdio.h>

i=48;

Output:

Value of the external integer is =48