Codes with Pankaj - Understanding C++ Storage Classes

Welcome to "Codes with Pankaj," your coding companion for unlocking the mysteries of C++. In this tutorial, we'll dive into the concept of storage classes, which play a crucial role in defining the scope, lifetime, and visibility of variables in your C++ programs. Whether you're a coding enthusiast or a seasoned programmer, understanding storage classes is essential for writing efficient and maintainable code.

Let's embark on this learning journey together with Pankaj!

1. Automatic Storage Class: Automatic storage class is the default storage class for local variables. Variables declared inside a function without any storage class specifier are of automatic storage class.

#include <iostream>

void automaticStorageClassExample() {
    // Automatic storage class example
    int localVar = 42;

    std::cout << "Automatic Variable: " << localVar << std::endl;
}

int main() {
    automaticStorageClassExample();

    return 0;
}
    

2. Register Storage Class: The register storage class is used to hint to the compiler that a variable will be heavily used, suggesting it be stored in a register for faster access.

#include <iostream>

void registerStorageClassExample() {
    // Register storage class example
    register int regVar = 100;

    std::cout << "Register Variable: " << regVar << std::endl;
}

int main() {
    registerStorageClassExample();

    return 0;
}
    

3. Static Storage Class: Static storage class is used to declare variables that retain their values between function calls. Explore the concept with examples demonstrating static variables.

#include <iostream>

void staticStorageClassExample() {
    // Static storage class example
    static int staticVar = 0;
    staticVar++;

    std::cout << "Static Variable: " << staticVar << std::endl;
}

int main() {
    staticStorageClassExample();
    staticStorageClassExample();
    staticStorageClassExample();

    return 0;
}
    

4. External Storage Class: The extern storage class is used to declare a variable that is defined in another file or at the top of the current file.

#include <iostream>

// External storage class example
extern int globalVar;

int main() {
    std::cout << "Global Variable (from another file): " << globalVar << std::endl;

    return 0;
}
    

5. Mutable Storage Class: The mutable specifier applies to class members of non-const objects, allowing them to be modified even in const member functions.

#include <iostream>

class MutableExample {
public:
    mutable int mutableVar;

    MutableExample() : mutableVar(0) {}

    void modifyVar() const {
        mutableVar++;
    }
};

int main() {
    MutableExample obj;
    obj.modifyVar();

    std::cout << "Mutable Variable: " << obj.mutableVar << std::endl;

    return 0;
}
    

Conclusion: Congratulations! You've explored the various storage classes in C++ with practical examples. Understanding storage classes is crucial for controlling the behavior of variables in your programs. Stay tuned for more coding adventures with Pankaj!