automatic storage class
automatic storage class

 

  • Automatic storage class is default storage class. All variables declared are of type Auto by default.
  • Automatic variables are allocated space in the variable on the stack and To declare a variable automatic storage class auto specified.
  • Automatic storage class variable are declare by ‘ auto ‘ class like as below the example.

          Example :– auto int i;

  • When declare a variable, if the omitted variable storage class is automatic in c programming language.

          Example :int i;

  • In c programming language , When declare an automatic variable initialization to be made explicit initial value is undefined.

Features :

  • The scope of an automatic variable is for the local and block, or any block within the block in c programming language.
  • Value of automatic variable storage in memory.
  • The lifetime of this automatic variable exists as long as Control remains in the block.
  • Default initial Value of this automatic variable is Garbage.

 

Now let’s see the syntax,example and output of the automatic storage class.

Syntax :

auto data_type variable_name;

Example 1 :

1#include<stdio.h>
2#include<conio.h>
3
4void addition();
5
6void main()
7{
8   addition();
9   addition();
10}
11
12void addition()
13{
14   auto int p = 0 ;
15   printf ( “%d \n”, p ) ;
16   p++;
17}

Output :
0
0

Example 2 :

void main()
{
   auto n = 10 ;
   {
      auto n = 20 ;
      printf(Num : %d”,n);
   }
printf(Num : %d”,n);
}

Output :
Num : 10
Num : 20

Here, In example-2 Two variables are declared in different blocks, so they are treated as different variables.