NOTES.md

Constructors in C++

Definition

A constructor is a special member function of a class that is automatically called when an object is created. It initializes the object’s data members.

• An object data member refers to a variable that is declared inside a class and belongs to each object created from that class. Each object has its own copy of these data members, which store the state or properties of that specific object.

Syntax

class ClassName {
public:
    ClassName(); // Constructor declaration
};
ClassName::ClassName() {
    // Initialization code
}

Key Points

• Constructors have the same name as the class.
• They do not have a return type (not even void).
• Can be overloaded (multiple constructors with different parameters).
• If no constructor is defined, the compiler provides a default constructor.
• Used to set initial values for data members or allocate resources.

Types of Constructors

• Default Constructor: No parameters.
• Parameterized Constructor: Takes arguments to initialize members.
• Copy Constructor: Initializes an object using another object of the same class.

Example

class Student {
    int id;
public:
    Student() { id = 0; } // Default constructor
    Student(int i) { id = i; } // Parameterized constructor
};

Best Practices

• Always initialize all data members.
• Use initializer lists for efficiency.
• Avoid complex logic in constructors.

Constructor Overloading:

The Process of Declaring multiple constructors with same name but different parameters is known as Constructor Overloading.

The constructors with the same name must differ in one of the following ways:

• Number of parameters
• Types of parambers
• Sequence of parameters