C Foundation

What is C? C Compiler Installation C Extensions C Compiler C Interpreter C Program Structure

C Basics

C Keywords C Data Types C Identifiers C Variables C Constant C Escape Sequences C Constant and Volatile C Typecast


What is Operator C Comma Operator C Arithmetic Operators C Relational Operators C Logical Operators C Bitwise Operators C Conditional Operators C : : Operator C Operator Priority

Basic IO's

Basic IO's C Formatted Functions C Unformatted Functions C Common Functions

Control Statements

What is Control Statement C if Statement C if else Statement C Nested if Statement C Else if Statement C Break Statement C Continue Statement C Switch Statement C Goto Statement


What is Control Loop C for Loop C Nested for Loop C while Loop C Nested while Loop C do while Loop C Nested do while loop


What is Function C User Defined Functions C Recursion C Passing Parameters


Scope C Local Scope C Global Scope

Storage Classes

What is Storage Class C Auto C Extern C Static C Register


What is Array C One Dimensional Array C Two Dimensional Array C Multi Dimensional Array C Arrays Of Strings


What is String C String Functions


What is Pointer C Pointers Arithmetic C Pointer to Pointer C Pointers and Arrays C Pointers and Strings C Pointer to Functions Void Pointers Null Pointers C Null and Void Pointer


What is Structure C Struct within Struct C Array within Structure C Pointer to Structure C Structure and Function C Enum C Bitfield Structure C Type def


What is Union


What is File C read a file C write a file C File Handling C Error Handling C Low Level Disk I/O C Other file functions

Memory Allocation

What is Memory Allocation C Malloc() C Calloc() C Free() C Realloc() C Coreleft()

C Reference

All ASCII Code Basic C Questions

C Interview

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The ones who are crazy enough to think they can change the world are the ones who do.
- Steve Jobs

C Auto Storage Class

What Is 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.
Auto Storage Class

Syntax - Auto Storage Class

auto int m1;

C program - Auto Storage Class

#include <stdio.h>
int main()
//declaration of automatic variables within main function
auto int m1 = 5;     //declaration of automatic variable with the keyword auto
int m2 = 10;      //declaration of automatic variable without the keyword auto
printf("The value of m1 : %d ", m1);
printf("\nThe value of m2 : %d ", m2);
return 0;
  • The value of m1 : 5
  • The value of m2 : 10


The automatic variables are declared and initialized inside the main function.


Keyword auto
Storage Type Memory
Scope Block Scope
Life Time Static life time
Visibility Local/Global
Default Value Garbage value
Default Storage Class Yes

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