BCA - OOPS and Data Structures

A constructor  is a special member function of a class that is automatically called when an object of the class is created . 

Key Point : Same as the class name , No return type , Called Automatically when object created.

## Different Types of Constructors

There are three main types of constructors in C++:

# Default Constructor

- A constructor that takes **no arguments**
- If you don’t define any constructor, the compiler creates one by default

Example:

class Student {
public:
    Student() {
        cout << "Default constructor called!" << endl;
    }
};

Student s1;  // Default constructor is called

# Parameterized Constructor

- A constructor that takes **one or more arguments**
- Used to initialize objects with specific values

Example:

class Student {
private:
    string name;
    int age;

public:
    // Parameterized constructor
    Student(string n, int a) {
        name = n;
        age = a;
    }

    void display() {
        cout << "Name: " << name << ", Age: " << age << endl;
    }
};

Student s2("Alice", 20);
s2.display();  // Output: Name: Alice, Age: 20

# Copy Constructor

- A constructor that initializes an object using **another object of the same class**
- It copies values from one object to another

Example:

class Student {
private:
    string name;
    int age;

public:
    Student(string n, int a) {
        name = n;
        age = a;
    }

    // Copy constructor
    Student(const Student &obj) {
        name = obj.name;
        age = obj.age;
    }

    void display() {
        cout << "Name: " << name << ", Age: " << age << endl;
    }
};

Student s1("Bob", 22);
Student s2 = s1;  // Copy constructor is called
s2.display();      // Output: Name: Bob, Age: 22