[1.1] Need of object-oriented programming [1.
2] Characteristics of object-oriented languages
1. OOP allows developers to break down a software program into 1.Class and Object: 1. Class: A blueprint for creating objects. A class
smaller, manageable pieces (objects and classes). Each class can defines a datatype by bundling data and methods that operate on the
represent a different part of the program, making it easier to data into one single unit.2. Object: An instance of a class. Objects are
understand and manage. created from classes and can contain data and methods.2.
2. Once a class is written, it can be reused across different parts of Encapsulation: Encapsulation involves bundling the data (attributes)
a program or even in different projects. This reduces redundancy and the methods (functions or procedures) that operate on the data into
and increases efficiency. a single unit, or class. It restricts direct access to some of the object's
3. OOP enables encapsulation, which is the concept of wrapping components, which can prevent the accidental modification of data.
data and methods that work on the data within one unit (class). This 3. Abstraction: Abstraction is the concept of hiding the complex
hides the internal state of the object and only exposes a limited implementation details and showing only the essential features of the
interface, which enhances security and reduces complexity. object. It helps in reducing programming complexity and effort.4.
4. Inheritance is a key feature of OOP that allows a new class to Inheritance: Inheritance allows a new class (child class) to inherit the
inherit properties and behaviours from an existing class. This properties and methods of an existing class (parent class). This
promotes code reusability and can simplify code maintenance. promotes code reusability and establishes a relationship between
5. Polymorphism allows methods to do different things based on different classes.5. Polymorphism: Polymorphism allows methods to
the object it is acting upon. This means a single interface can be be defined in a way that they can be used interchangeably. It means
used with different underlying forms (data types). that the same operation can behave differently on different classes.
6. The modular nature of OOP, along with its reusability and ability Polymorphism is achieved through method overloading and method
to model real-world scenarios more closely, can lead to faster overriding.6. Dynamic Binding: Dynamic binding (also known as
development times and higher-quality software. late binding) refers to the runtime decision about which method to
7. OOP makes it easier to manage and scale larger software invoke. In OOP, methods can be overridden in the derived classes,
projects. Changes in the software can be made with minimal impact and the call to these methods is resolved at runtime.7. Modularity
on other parts of the program, and it’s easier to track down bugs. encourages the division of a program into small, manageable, and
8.OOP allows for more flexible and dynamic design patterns. interchangeable modules. Each module is a class that can be
Developers can create complex systems more easily and ensure that developed, tested, and debugged independently.
the design of the system can be extended or modified with minimal
impact.
[1.4] Constructors [1.3] class, Objects as data types
1. A constructor has the same name as the class in which it is Class: A class in C++ is a user-defined data type that serves as a
defined. blueprint for creating objects. It defines a set of properties (data
2. It does not have a return type, not even void. members) and behaviours (member functions or methods) that the
3.Constructors are invoked automatically when an object is created. objects created from the class will have.1. These are variables that
4.The programmer does not need to explicitly call the constructor. hold data specific to the class.2. They define the properties or
5. Constructors can be overloaded, meaning a class can have more attributes of the class.3. These are functions that operate on the data
than one constructor, each with different parameters. members of the class. 4. They define the behaviours or actions that the
6.This allows objects to be initialized in different ways. objects of the class can perform. 5.Members declared under this
7. Constructors are used to initialize the data members of a class. specifier can be accessed from outside the class. 6.Members declared
8.They can set default values, allocate resources, and perform any under this specifier cannot be accessed from outside the class; they
setup required for the object. are accessible only within the class itself. 7.Members declared under
Types of Constructors: this specifier can be accessed within the class and by derived classes.
1.Default Constructor:1. A constructor that takes no arguments.2. 8.Special member functions that are automatically called when an
If no constructors are defined in a class, the compiler provides a object of the class is created. 9.Used to initialize objects. 10.Special
default constructor. member functions that are automatically called when an object of the
2. Parameterized Constructor: A constructor that takes one or more class is destroyed.
arguments. Objects
3. Copy Constructor: A constructor that takes a reference to a jet of An object is an instance of a class. When a class is defined, no memory
the same class as an argument. is allocated until an object of that class is created. Objects can interact
4. Move Constructor: Used to transfer resources from a temporary with each other by sending messages (calling member functions).
object to a new object, improving performance by avoiding Objects are the basic run-time entities in an object-oriented system.
unnecessary copying. 1.The state of an object is defined by the values of its data members.
Destructor: 2. Each object can have a different state, depending on the values of
1. While not a constructor, the destructor is closely related. its properties.3. The behaviour of an object is defined by its member
2. It is a special member function that is called when an object goes functions. 4.Different objects can exhibit different behaviours based
out of scope or is explicitly deleted. on their state. 5.Each object has a unique identity, even if its state is
3.The destructor is used to release resources acquired by the object identical to that of another object. 6.Identity is usually represented by
during its lifetime. the object's memory address. 7.It restricts direct access to some of an
object's components, which can prevent the accidental modification
of data.8. The concept of hiding the complex implementation details
and showing only the essential features of an object.
