4. C++ OOP: Classes, Objects, Constructors & Destructors

Comprehensive Guide: Access specifiers (public/private), default & parameterized constructors, destructors & dynamic new/delete

Module 1: Classes, Objects & Access Specifiers

Blueprints and object instances bundling data members and member functions.

🇬🇧 English Definition

A Class is a user-defined blueprint that defines data members and member functions, while an Object is a real-world instance of that class.

🇮🇳 Hinglish Definition

Class ek naksha (blueprint) hota hai, aur Object us nakashe se bani asli cheez hoti hai.

Core Concepts & Rules

private: Accessible ONLY inside the class.
public: Accessible from anywhere outside the class.
protected: Accessible inside the class and derived child classes.

🔍 Line-by-Line Code Breakdown

Line 1-10: Define Student class with private member name and public setter/getter methods.
Line 13: Instantiate Student object s1 in main().

💻 Practical C++ Code Example - Classes, Objects & Access Specifiers

using namespace std;

class Student {
private:
    string name;
public:
    void setName(string n) { name = n; }
    string getName() { return name; }
};

int main() {
    Student s1;
    s1.setName("Instructor Student");
    cout << "Student Name: " << s1.getName() << endl;
    return 0;
}

📤 Compiled C++ Output:

Student Name: Instructor Student

Module 2: Constructors, Destructors & Dynamic Memory (new/delete)

Automatic object initialization and resource cleanup.

🇬🇧 English Definition

A Constructor is a special member function executed automatically upon object creation, whereas a Destructor (~ClassName) executes automatically when an object goes out of scope.

🇮🇳 Hinglish Definition

Constructor object bante hi automatically call hokar fields initialize karta hai. Destructor (~Class) object destroy hone par RAM clean karta hai.

Core Concepts & Rules

Constructor has the exact same name as the class and NO return type.
Destructor name starts with tilde symbol (~ClassName()).
new operator allocates heap memory; delete releases heap memory.

🔍 Line-by-Line Code Breakdown

Line 3-5: Parameterized Constructor initializing course name.
Line 6-8: Destructor ~Course printing cleanup message.
Line 12: Instantiate Course c1('C++ OOP') triggers constructor automatically.

💻 Practical C++ Code Example - Constructors, Destructors & Dynamic Memory (new/delete)

using namespace std;

class Course {
public:
    string title;
    Course(string t) {
        title = t;
        cout << "Constructor Called for: " << title << endl;
    }
    ~Course() {
        cout << "Destructor Executed! Memory Cleaned." << endl;
    }
};

int main() {
    {
        Course c1("C++ OOP Masterclass");
    } // c1 goes out of scope here -> Destructor runs
    return 0;
}

📤 Compiled C++ Output:

Constructor Called for: C++ OOP Masterclass Destructor Executed! Memory Cleaned.