Oops Concepts
Oops
Key Words
OOPS Key words & Definitions
In Object-Oriented Programming (OOP), various keywords and concepts define how objects and classes interact.
Below is a comprehensive list:
1. Class
A class is like a blueprint for creating objects.
📌 Example: A Car class can define attributes like color, brand, speed and methods like start() and stop().
2. Object
An object is an instance of a class.
📌 Example: A BMW Car object is created from the Car class and has specific properties like black color and 220 km/h max speed.
3. Encapsulation
Encapsulation hides the internal details of an object and only exposes necessary parts.
📌 Example: A bank account class hides the balance variable, allowing access only through deposit() and withdraw() methods.
4. Inheritance
A child class can inherit properties from a parent class.
📌 Example: A Bird class has a function called fly(). A Parrot class inherits from it and can also fly without redefining the function.
5. Polymorphism
The same function behaves differently in different scenarios.
📌 Example: A makeSound() function produces "Meow" for a Cat and "Bark" for a Dog.
6. Abstraction
Abstraction hides unnecessary details and only exposes essential features.
📌 Example: When you press the brake pedal, the car stops. You don’t need to know how the brake mechanism works internally.
7. Interface
An interface defines a contract that must be followed.
📌 Example: A TV Remote has buttons for volume and power. No matter the brand, every TV follows the same remote interface.
8. Constructor
A constructor initializes an object when it is created.
📌 Example: When you buy a smartphone, it comes with default settings like brightness, volume, and wallpaper.
9. Destructor
A destructor is used to free memory when an object is destroyed.
📌 Example: When you close a game, it releases RAM used by the game so that the system can use it for other tasks.
10. Static
A static variable or method belongs to the class itself, not any specific object.
📌 Example: A company’s tax rate is the same for all employees, so it is declared static.
11. This Keyword
The this keyword refers to the current instance of the object.
📌 Example: If Praveen is an object in a Person class, the this keyword ensures that his name is correctly assigned.
12. Super Keyword
The super keyword calls the parent class’s methods or constructors.
📌 Example: A Manager class inherits from an Employee class. Using super, the Manager can call the Employee's salary calculation method.
13. Final Keyword
The final keyword prevents modification of a variable, method, or class.
📌 Example: The value of Pi (3.1416) in a Math class is set as final so it can’t be changed.
14. Abstract Class
An abstract class can’t be instantiated but can be inherited.
📌 Example: A Vehicle class defines a move() function but doesn’t specify how. A Car class and a Bike class implement move() in their own way.
15. Pointer (C++ Specific)
A pointer stores the memory address of an object or variable.
📌 Example: A Google Maps app stores your current location (pointer) and updates it in real-time.
16. Union (C & C++ Specific)
A union allows different data types to share the same memory location.
📌 Example: A smartphone has a single memory chip that stores contacts, messages, and apps, but at different times.
17. Float Data Type
A float is used to store decimal values.
📌 Example: The temperature in a weather app is stored as a float (e.g., 27.5°C).
18. Multiple Inheritance (C++ Specific)
A class can inherit from multiple parent classes.
📌 Example: A Smartphone inherits from both Camera (to take pictures) and Phone (to make calls).
19. Virtual Function (C++ Specific)
A virtual function allows function overriding in derived classes.
📌 Example: A Gaming Console has a play() function. A PS5 and Xbox redefine the play() function differently.
20. Interface vs. Abstract Class
Interface → Only method declarations, no implementation.
Abstract Class → Can have both defined and undefined methods.
📌 Example:
A USB Port is an interface → Every device must follow its standard.
A Car is an abstract class → Some features are implemented.
21. Assign
Assigning means giving a value to a variable.
📌 Example: When filling out a form, you assign your name to the "Name" field.
22. Define
Defining means creating something with a specific structure like a function or variable.
📌 Example: Defining a recipe for making a cake – you provide ingredients and instructions.
23. Declare
Declaring means introducing a variable or function without assigning a value.
📌 Example: You declare a meeting time before finalizing the exact schedule.
24. Variable
A variable is a named storage location that holds data.
📌 Example: A shopping cart stores the total price, which changes when you add or remove items.
25. Protocol
A protocol is a set of rules for communication.
📌 Example: In WhatsApp messaging, both sender and receiver follow a protocol to send and receive messages correctly.
26. Syntax
Syntax is the set of rules that define how code should be written.
📌 Example: A grammar book defines the correct way to write sentences in English.
27. Operators
Operators perform mathematical or logical operations on values.
📌 Example: A calculator uses operators like + (addition), - (subtraction), * (multiplication), and / (division).
28. Operands
Operands are the values used with operators.
📌 Example: In 5 + 3, the numbers 5 and 3 are operands, and + is the operator.
29. Functions
A function is a reusable block of code that performs a task.
📌 Example: A coffee machine has functions like makeEspresso(), makeCappuccino(), and addMilk().
30. Constants
A constant is a fixed value that doesn’t change.
📌 Example: The value of π (3.1416) remains the same in mathematics.
31. Header
A header file contains declarations and functions used in a program.
📌 Example: A table of contents in a book lists all sections before reading.
32. Global & Local Variables
Global Variable: Accessible anywhere in the program.
Local Variable: Only accessible within a specific function.
📌 Example:A company’s CEO (Global) can access everything.
A team manager (Local) can only manage his own team.
33. Conditions
Conditions control what happens based on a decision.
📌 Example: If it rains, you carry an umbrella; otherwise, you don't.
34. Parenthesis ()
Parentheses group expressions and control the order of operations.
📌 Example: In a mathematical equation (2 + 3) × 4, the parentheses ensure that 2 + 3 is calculated first.
35. Arguments
Arguments are values passed into functions to perform a task.
📌 Example: A pizza order function can take arguments like size, toppings, and crust type.
36. Objects
Objects are instances of a class, containing data (attributes) and actions (methods).
📌 Example: A smartphone object has attributes like brand, model, and battery life and methods like makeCall() and takePhoto().
37. Structures
A structure is a collection of variables of different data types grouped together.
📌 Example: A student record has different fields like Name (String), Age (Integer), and Marks (Float).
38. Array
An array is a collection of values stored in a single variable.
📌 Example: A playlist stores multiple songs in one list.
39. List
A list is similar to an array but can store different data types and is more flexible.
📌 Example: A to-do list contains tasks like "Buy groceries" (String) and "2 hours workout" (Integer).
40. Integer
An integer is a whole number (without decimals).
📌 Example: The number of students in a class (e.g., 50) is stored as an integer.
41. Float
A float is a number with a decimal point.
📌 Example: A temperature reading (e.g., 36.5°C) is stored as a float.
42. Data Type
A data type defines the kind of value a variable can hold (integer, float, string, etc.).
📌 Example: A passport form has fields with different data types like Name (String), Age (Integer), and Height (Float).
43. Union
A union allows different variables to share the same memory location.
📌 Example: A digital clock displays either hours-minutes-seconds or date-month-year, but only one at a time.
44. Enumeration (enum)
An enum is a set of named constants.
📌 Example: The days of the week (Monday, Tuesday, etc.) can be stored as an enum.
45. Inline Function
An inline function is a function that is expanded at the point of call, rather than being executed separately.
📌 Example: A shortcut key (Ctrl + C) directly executes the copy function instead of calling a separate menu.
