What is an auto storage class in C language?

There are four storage classes in C programming language, which are as follows −

• auto
• extern
• static
• register

Automatic variables / Local variables

The keyword is auto. These are also called as local variables.

Scope

• Scope of a local variable is available within the block in which they are declared.
• These variables are declared inside a block.
• Default value: Garbage value.

Algorithm

The algorithm is given below −

START
Step 1: Declare and initialize auto int i=1
   I. Declare and initialized auto int i=2
      I. declare and initialized auto int i=3
      II. print I value//3
   II Print I value //2
Step 2: print I value
STOP

Example

Following is the C program for auto storage class −

#include<stdio.h>
main ( ){
   auto int i=1;{
      auto int i=2;{
         auto int i=3;
         printf ("%d",i)
      }
      printf("%d", i);
   }
   printf("%d", i);
}

Output

The output is stated below −

3 2 1

Consider another program for auto storage class.

Example

#include<stdio.h>
int mul(int num1, int num2){
   auto int result; //declaration of auto variable
   result = num1*num2;
   return result;
}
int main(){
   int p,q,r;
   printf("enter p,q values:");
   scanf("%d%d",&p,&q);
   r = mul(p, q);
   printf("multiplication is : %d\n", r);
   return 0;
}

Output

The output is stated below −

Run 1: enter p,q values:3 5
multiplication is : 15
Run 2: enter p,q values:6 8
multiplication is : 48