C++ Tutorial Index

C++ Tutorial C++ History C++ Installation C++ First Program C++ cin and cout C++ Data type C++ Variable C++ operator C++ Keywords

C++ Control Statements

C++ If C++ Nested if C++ If-else C++ If-else-if C++ Switch C++ Break C++ Continue C++ Goto C++ For loop C++ While loop C++ Do while loop

C++ Functions

C++ Call by Value C++ Call by Reference C++ Recursion Function C++ Inline function C++ Friend function

C++ Arrays

Single dimension array Two dimension array

C++ Strings

C++ Strings

C++ Inheritance

C++ Inheritance Single level Inheritance Multilevel Inheritance Multiple Inheritance Hierarchical Inheritance Hybrid Inheritance

C++ Polymorphism

C++ Polymorphism C++ Overloading C++ Overriding C++ Virtual Function

C++ Pointers

C++ Pointers C++ this pointer

C++ Exception Handling

C++ Exception Handling

C++ Constructors

C++ Constructors Default Constructor Parameterize Constructor Copy constructor Constructor Overloading Destructor

C++ File Handling

C++ File Handling C++ Writing to file C++ Reading file C++ Close file


C Vs C++ C++ Comments C++ Data Abstraction C++ Identifier C++ Memory Management C++ Storage Classes C++ Void Pointer C++ Array To Function C++ Expressions C++ Features C++ Interfaces C++ Encapsulation std::min in C++ External merge sort in C++ Remove duplicates from sorted array in C++ Precision of floating point numbers Using these functions floor(), ceil(), trunc(), round() and setprecision() in C++ C++ References C++ Friend Functions C++ Mutable keyword Unary Operators in C++ Initialize Array of objects with parameterized constructors in C++ Differences between #define & const in C/C++ C++ Program to Implement Shell Sort C++ Program to Implement Merge Sort Storage Classes in C Vector resize() in C++ Passing by Reference Vs. Passing by the pointer in C++ Free vs delete() in C++ goto statement in C and C++ C++ program to read string using cin.getline() C++ String Concatenation Heap Sort in C++ Swap numbers in C++ Input Iterators in C++ Fibonacci Series in C++ C ++ Program: Alphabet Triangle and Number Triangle C++ Program: Matrix Multiplication C++ Program to Print Fibonacci Triangle Stack in C++ Maps in C++ Queue in C++ C++ Bitset C++ Algorithms Priority Queue in C++ C++ Multimap C++ Deque Function Pointer in C++ Sizeof() Operators in C++ C++ array of Pointers free() Vs delete in C Timsort Implementation Using C++ CPP Templates C++ Aggregation C++ Enumeration C++ Math Functions C++ Object Class C++ Queue Initialize Vector in C++ Vector in C++ C++ STL Components Function overloading in C++ C++ Maximum Index Problem C++ find missing in the second array C++ Program to find the product array puzzle C++ Program To Find Largest Subarray With 0 Sum C++ Program To Move All Zeros To The End Of The Array C++ Program to find the element that occurs once C++ Program to find the largest number formed from an array Constructor Vs Destructor C++ Namespaces C++ OOPs Concept C++ Static C++ Structs C++ Try-Catch C++ User Defined Exceptions C++ Virtual Destructor C++ vs C# Malloc() and new in C++ Palindrome Number Program in C++ Snake Code in C++ Splitting a string in C++ Structure Vs Class in C++ Virtual Function Vs Pure Virtual Function C++ Bidirectional Iterators C++ Forward Iterators C++ Iterators C++ Output Iterators C++ Range-based For Loop Converting string into integer in C++ LCM Program in C++ Type conversion in C++ Add two numbers using the function in C++ Advantage and disadvantage friend function C++ Armstrong Number Program in C++ ATM machine program in C++ using functions Binary to Decimal in C++ Bit Manipulation in C++ C++ Constructor C++ Dijkstra Algorithm Using the Priority Queue C++ int into String C++ Signal Handling Decimal to Binary in C++ Decimal to Hexadecimal in C++ Decimal to Octal in C++ Factorial Program in C++ Function in C++ Hexadecimal to Decimal in C++ Octal to Decimal in C++ Reverse a Number in C++ Structure Vs Class in C++ C++ Forward Iterators C++ Output Iterators C++ Prime number program Char Array to String in C++ Constructor Overloading in C++ Default arguments in C++ Different Ways to Compare Strings in C++ Dynamic Binding in C++ Program to convert infix to postfix expression in C++ SET Data Structure in C++ Upcasting and Downcasting in C++ Reverse an Array in C++ Fast Input and Output in C++ Delete Operator in C++ Copy elision in C++ C++ Date and Time C++ Bitwise XOR Operator Array of sets in C++ Binary Operator Overloading in C++ Binary Search in C++ Implementing the sets without C++ STL containers Scope Resolution Operator in C++ Smart pointers in C++ Types of polymorphism in C++ Exception Handling in C++ vs Java Const Keyword in C++ Type Casting in C++ Static keyword in C++ vs Java Inheritance in C++ vs Java How to concatenate two strings in C++ Programs to Print Pyramid Patterns in C++ swap() function in C++ Structure of C++ Program Stringstream in C++ and its applications rand() and srand() in C / C++ C++ Ternary Operator C++ Scope of Variables While Loop Examples in C++ Star pattern in C++ using For Loops For Loop Examples in C++ Do-While Loop Examples in C++ Top 5 IDEs for C++ That You Should Try Once Assertions in C/C++ C++ Convert Int to String Continue in C++ While loop Diamond Pattern in C++ using For Loop How to Reverse a String in C++ using Do-While Loop How to Reverse a String in C++ using For Loop How to Reverse a String in C++ using While Loop Infinite loop in C++ Loops in C++ Returning Multiple Values from a Function using Tuple and Pair in C++ wcscpy(), wcslen(), wcscmp() Functions in C++ Auto keyword in C++ C++ 11 vs C++ 14 vs C++ 17 C++ STL (Standard Template Library) Differences Between C Structures and C++ Structures Divide by Zero Exception in C++ Dynamic Constructor in C++ Dynamic Memory Allocation in C++ Find the Size of Array in C/C++ without using sizeof() function Floating Point Operations and Associativity in C, C++ and Java Hello World Program in C++ How to create a table in C++ How to Setup Environment for C++ Programming on Mac Implementation of a Falling Matrix in C++ Message Passing in C++ Pointer to Object in C++ Templates in C++ vs Generics in Java Ways to Copy a Vector in C++ What does Buffer Flush mean in C++ sort() function in C++ Structure Sorting (By Multiple Rules) in C++ Similarities between C++ and Java std::distance in C++ Array program in C++ C++ Tricks for Competitive Programming Desired Capabilities in Selenium Web Driver in C++ Socket Programming in C++ Template Specialization in C++ Classes and Objects in C++ Convex hull Algorithm in C++ DES in C++ C++ vardiac() function Difference between Two Sets in C++ Difference between Exit and Return Structured Binding in C++ Differences between Local and Global Variable Bitwise Operator vs Logical Operator Difference between OOP and POP in C++ Fork in C++ Functors in C++ How to call a void function in C++ How to create a directory or folder in C/C++ How to create a library in C++ How to create a stack in C++ How to create the Processes with Fork in C++ How to Handle Divide by Zero Exception in C++ Lambda Expression in C++ Pattern programs in C++ Roadmap to C++ Programming Substring in C++ Virtual base class in C++ Bits stdc++.h in C++ Top 14 Best Free C++ IDE (Editor & Compiler) for Windows in 2022 Bitmasking in C++ Auto Keyword in C++ Features of OOPS in C++ Hospital Management Project in C++ How to Declare Unordered Sets in C++ How to Sort an Array in C++ Include Guards in C++ Iostream in C++ Method overriding in C++ How to run program in turbo c++ How to Use Getline in C++ Leap Year Program in C++ Naming Convention in C++ New Operator in C++ Nullptr in C++ Object Slicing in C++ Principles of Object-Oriented Programming in C++ Processing strings using std string stream in C++ Pure Virtual Function in C++ With Example Program Random Number Generator in C++ Singleton Design Pattern in C++ Size_t Data Type in C++ Skyline Problem in C++ System() function in C++ Web Development in C++ Data Hiding in C++ Difference between exit() and _Exit() in C++ Hashing in C++ Object in C++ Sum of all Elements between k1’th and k2’th Smallest Elements Virtual class in C++ Vector Size in C++ Top best IDEs for C/C++ Developers in 2022 Tensorflow in C++ Sliding Window Technique in C++ Reverse String Word-Wise in C++ Returning a Function Pointer from a Function in C/C++ RTTI in C++ Pthreads or POSIX Threads in C++ Reserved Keywords in C++ Passing a Vector to a function in C++ 10 Best C and C++ Books for Beginners & Advanced Programmers Add two numbers represented by two arrays in C++ Array of Object in C++ C++ Program For FCFS Containership in C++ Counting Frequencies of Array Elements in C++ Decltype type Specifier in C++ Dynamic _Cast in C++ Difference between int main() and int main(void) in C/C++ Depth First Search Program to Traverse a Graph in C++ Features and Use Of Pointers in C/C++ Fread Function in C++ Programming Fscanf Function in The C++ Functions in C++ With Types and Examples Gmtime Function in C/C++ How is Multiset Implemented in C++ How to Build a Program in C++ How to Declare a 2d Array Dynamically in C++ inheritance Program in C++ int Max and int Min in C/C++ is It Fine to Write Void Main Or Main in C/C++ How to create a button in C++ abs() function in C++ Compile Time Polymorphism in C++ Division in C++ Factorial of a Number in C++ using while Loop Multiset in C++ 4 Pillars of OOPs Approach in C++ Backtracking Time Complexity in C++ C++ Global Variable C++ Pipe Tutorial Observer Design Pattern in C++ Private Inheritance in C++ Pthread in C++ Parameters SDL library in C++ with Examples Pointers in C++ Abstract Factory Design Pattern in C++

Storage Classes in C

Storage Classes in C

Storage Classes are used to define the variable and function property. These functionalities include basically the scope, accessibility, and lifetime that help us detect the existence of a particular variable during a program's runtime.

  • auto
  • register
  • static
  • extern

The auto Storage Class

For all local variables, the auto storage class is the default storage class.

   auto int gender;

The example above differentiates two variables in the same storage class.

Only functions, i.e., local variables, can be used in 'auto'

The static Storage Class

The static storage class instructs the compiler to retain a local variable in existence throughout the program's lifespan, instead of generating it and deleting it as it comes in and goes out of control. Hence, the stratification of local variables helps maintain their values between function calls.

Also, the static modifier may be applied to global variables. When this is achieved, it causes the scope of that variable to be limited to the file that declares it to be in.

The register Storage Class

This class of storage declares registry variables that have the same functionality like the auto variables. The only difference is that if a free register is available, the compiler tries to store those variables in the microprocessor's register. It makes use of registry variables much faster than those stored in the memory during the initialization of the program. If there is no free register available, these are stored only in the memory. Generally, several variables are defined with the register keyword, which helps in increasing the system runtime to be obtained within a program. An important and interesting point to note here is that we cannot use the pointers to retrieve the address of a registry variable.

register int  token;

In C programming language, when static has been used on a global variable, it allows all members of its class to share only one copy of that item.

#include <stdio.h>
/* function declaration */
void function(void);
static int count = 10; /* global variable */
main() {
   while(count--) {
   return 0;
/* function definition */
void function( void ) {
   static int k = 10; /* local static variable */
   printf("k is %d and count is %d\n", k, count);


Storage Classes in C

The extern Storage Class

The extern storage class is used to provide a comparison of a global variable that is accessible to ALL the files in the program. However, when you use 'external,' the variable cannot be initialized; it points the name of the variable to a predefined storage location.


#include <stdio.h>
int x;
void autoStorageClass()
    printf("\nDemonstrating auto class\n\n");
    // declaring an auto variable (simply
    // writing "int k=30;" works as well)
    auto int k = 30;
    // printing the auto variable 'a'
    printf("Value of the variable 'k'"
           " declared as auto: %d\n",
void registerStorageClass()
    printf("\nDemonstrating register class\n\n");
    // declaring a register variable
    register char b = 'G';
    // printing the register variable 'b'
    printf("Value of the variable 'b'"
           " declared as register: %d\n",
void externStorageClass()
    printf("\nDemonstrating extern class\n\n");
    // telling the compiler that the variable
    // z is an extern variable and has been
    // defined elsewhere (above the main
    // function)
    extern int x;
    // printing the extern variables 'x'
    printf("Value of the variable 'x'"
           " declared as extern: %d\n",
    // value of extern variable x modified
    x = 2;
    // printing the modified values of
    // extern variables 'x'
    printf("Modified value of the variable 'x'"
           " declared as extern: %d\n",
void staticStorageClass()
    int t = 0;
    printf("\nDemonstrating static class\n\n");
    // using a static variable 'y'
    printf("Declaring 'y' as static inside the loop.\n"
           "But this declaration will occur only"
           " once as 'y' is static.\n"
           "If not, then every time the value of 'y' "
           "will be the declared value 5"
           " as in the case of variable 'p'\n");
    printf("\nLoop started:\n");
    for (t = 1; t < 5; t++) {
        // Declaring the static variable 'y'
        static int y = 5;
        // Declare a non-static variable 'p'
        int p = 10;
        // Incrementing the value of y and p by 1
        // printing value of y at each iteration
        printf("\nThe value of 'y', "
               "declared as static, in %d "
               "iteration is %d\n",
               t, y);
        // printing value of p at each iteration
        printf("The value of non-static variable 'p', "
               "in %d iteration is %d\n",
               t, p);
    printf("\nLoop ended:\n");
int main()
    printf("A program to demonstrate."
           " Storage Classes in C\n\n");
    // To demonstrate auto Storage Class
    // To demonstrate register Storage Class
    // To demonstrate extern Storage Class
    // To demonstrate static Storage Class
    // exiting
    printf("\n\nStorage Classes demonstrated");
    return 0;


Storage Classes in C