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Introduction to OOPs

Definition

Object-Oriented Programming is basically a programming style that we used to follow in modern programming. It primarily revolves around classes and objects. Object-Oriented programming or OOPs refers to the language that uses the concept of class and object in programming.

Class

A class is a logical entity used to define a new data type. A class is a user-defined type that describes what a particular kind of object will look like. Thus, a class is a template or blueprint for an object. A class contains variables, methods, and constructors.

Syntax:

class class_name {
    // class body
    // properties 1
    // methods
};

Object

An object is an instance of a Class. It is an identifiable entity with some characteristics and behavior. Objects are the basic units of object-oriented programming. It may be any real-world object like a person, chair, table, pen, animal, car, etc.

Syntax to create an object in C++:

    class_name objectName;

Syntax to create an object dynamically in C++:

    class_name * objectName = new class_name();

The class’s default constructor is called, and it dynamically allocates memory for one object of the class. The address of the memory allocated is assigned to the pointer, i.e., objectName.

Creating a class Animal and objects mammal, amphibian and bird:

// creating Animal class
class Animal {
public:
    bool gives_birth;
    bool lay_egg;
    bool live_in_ground;
    bool live_in_water;
    bool have_wings;
};

int main()
{
    // creating an object of animal class
    Animal mammal;
    mammal.gives_birth = true;
    mammal.lay_egg = false;
    mammal.live_in_ground = true;
    mammal.live_in_water = false;
    mammal.have_wings = false;

    Animal amphibian;
    amphibian.gives_birth = false;
    amphibian.lay_egg = true;
    amphibian.live_in_ground = true;
    amphibian.live_in_water = true;
    amphibian.have_wings = false;

    Animal bird;
    bird.gives_birth = false;
    bird.lay_egg = true;
    bird.live_in_ground = true;
    bird.live_in_water = false;
    bird.have_wings = true;
}

Features of OOPs:

Four major object-oriented programming features make them different from non-OOP languages:

  • Abstraction is the property by virtue of which only the essential details are displayed to the user.
  • Inheritance allows you to create class hierarchies, where a base class gives its behavior and attributes to a derived class.
  • Polymorphism ensures that it will execute the proper method based on the calling object’s type.
  • Encapsulation allows you to control access to your object’s state while making it easier to maintain or change your implementation at a later date.

Need of object-oriented programming?

  • To make the development and maintenance of projects more effortless.
  • To provide the feature of data hiding that is good for security concerns.
  • We can solve real-world problems if we are using object-oriented programming.
  • It ensures code reusability.
  • It lets us write generic code: which will work with a range of data, so we don't have to write basic stuff over and over again.

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