OOP Cheatsheet by Love Babbar

Links and resources for strengthening the concepts of Object Oriented Programming [Java and C++] To the point for Interview Preparation and sufficient for Academics.

Love Babbar CheatSheet : cheatsheet
Love Babbar Video : video

Useful Links

SNo	Topic	Link	Language
1	Virtual Functions	view	C++
2	Polymorphism	view	C++

Resources

SNo	Language	Link
1	C++	view
2	Java	view

Overview

SNo	Topic	Link	Date Completed
1	What is OOP ?	view	not done
2	How OOP is related to real world ?	view	not done
3	Why to study OOPs ?	view	not done
4	Limitations of OOPs	view	not done
5	When we say that "X" language is object oriented programming language, then what does we mean by that ?	homework	not done

Classes

SNo	Topic	Link	Date Completed
1	Difference between Structure and Class	view	not done
2	Similarities between Structure and Class	view	not done
3	When to use Structure over Class	homework	not done
4	Access Modifiers	view	not done
5	Member Function	view	not done
6	Constructor	view	not done
7	Destructor	view	not done

Access Specifiers

There are 4 access modifiers in C++ :

public
private
protected
friend
protected friend

Member functions

Inside Class Function --> inline keyword
Outside Class Function --> scope resolution operator (::)

Constructor

SNo	Topic	Link	Date Completed
1	Default Constructor	-	not done
2	Parameterised Constructor	-	not done
3	Copy Constructor : Deep vs shallow copy	view	not done
4	Copy Constructor : copy ctor vs assignment	view	not done
5	Virtual Constructor	view	not done
6	Virtual Copy Constructor	view	not done
7	Constructor vs member functions	view	not done
8	Constructor Overloading	view	not done

Destructor

SNo	Topic	Link	Date Completed
1	Private Destructor	view	not done
2	Virtual Destructor	view	not done
3	Pure Virtual Destructor	view	not done
4	Destructor vs member functions	view	not done
5	Multiple Destructors in one class ?	view	not done
6	When to write user defined Destructor ?	view	not done
7	Can a Destructor be virtual ?	view	not done

Objects

SNo	Topic	Link	Date Completed
1	difference btw Class and Object	view	not done
2	Real world Analogy btw Class and Object	view	not done

Important Keywords

SNo	Topic	Link	Date Completed
1	static	view	not done
2	virtual	view	not done
3	abstract	view	not done
4	final	view	not done
5	explicit	view	not done
6	this	view	not done
7	new	view	not done
8	const	view	not done
9	super	view	not done

Features of OOPs :

Polymorphism
Inheritance
Encapsulation
Abstraction

Polymorphism

SNo	Topic	Link	Date Completed
1	What is Polymorphism ?	view	not done
2	Need of Polymorphism ?	view	not done
3	Function / Operator Overloading	view	not done
4	Function Overriding	view	not done
5	Virtual Function	view	not done
6	Virtual Class	view	not done
7	Derived Class	view	not done
8	Can Virtual Function be private ?	view	not done
9	Inline Virtual Function	view	not done
10	Abstract Class	view	not done
11	Pure Virtual Function	view	not done
12	Pure Virtual Destructor	view	not done

Polymorphism is categorised into 2 types :

Function / Operator Overloading
Function Overriding

Function / Operator Overloading

SNo	Topic	Link	Date Completed
1	Compile time Polymorphism	view	not done
2	Functions cannot be overloaded in C++	view	not done
3	Operators that cannot be overloaded in C++	view	not done

Note : Function Overriding is also called run-time Polymorphism.

5 Types of Inheritance

Single
Mutliple
Hierarchical
Multilevel
Hybrid / Virtual

Inheritance

SNo	Topic	Link	Date Completed
1	What is Inheritance ?	view	not done
2	Need of Inheritance	view	not done
3	Can OOP exist without Inheritance ?	view	not done
4	Types of Inheritance	view	not done
5	Real life examples of Multiple Inheritance	view	not done
6	Limitations of Inheritance	view	not done
7	Sealed Modifier	view	not done
8	Calling base method without creating instance	view	not done
9	new vs override	view	not done
10	Why JAVA doesn't support Multiple Inheritance	view	not done
11	Dreaded diamond in Multiple Inheritance	view	not done
12	Object Slicing	view	not done
13	Hide base class methods in JAVA	view	not done
14	Does overloading work with Inheritance	view	not done
15	Polymorphism vs Inheritance	view	not done
16	Generalization vs Aggregation vs Composition	view	not done
17	Friend Function / Class	homework	not done
18	Local Class, nested Class	homework	not done
19	Simulating Final Class	homework	not done

Note: If class A inherits from class B, then what all are inherited from parent class and size calculation. Explore all possible combinations

Encapsulation

SNo	Topic	Link	Date Completed
1	What is Encapsulation ?	view	not done
2	Advantages of Encapsulation	view	not done
3	How to achieve Encapsulation	view	not done
4	Code / Implementation of Encapsulation	view	not done
5	Real world example of Encapsulation	view	not done

Encapsulation is the combination of Data hiding and Abstraction

Abstraction

SNo	Topic	Link	Date Completed
1	What is Abstraction ?	view	not done
2	When to Abstraction ?	homework	not done
3	How to achieve Abstraction ?	view	not done
4	Encapsulation vs Abstraction	view	not done
5	Interface vs Abstract classes in JAVA	view	not done

Data abstraction is a way of hiding the implementation details and showing only the functionality to the users.

How to achieve : 
  1) C++  --> Access specifiers and header files
  2) JAVA --> Interfaces and Abstract classes

Design Interview Questions

SNo	Topic	Link	Date Completed
1	Design a hashmap	view	not done
2	Design a LRU cache	view	not done
3	Design a Call Center	view	not done
4	Design a deck of cards	view	not done
5	Design a parking lot	view	not done
6	Design an online chat	view	not done

Miscellaneous

SNo	Topic	Link	Date Completed
1	Static and Dynamic Binding	view	not done
2	Message Passing	view	not done
3	C vs C++ vs JAVA	view	not done
4	Procedural vs OOPs	view	not done
5	Why JAVA is not purely OOB	view	not done
6	Is array primitive or object in JAVA	view	not done
7	Early and late binding	view	not done
8	Default access modifier in class	view	not done
9	No. of instances for an abstract class	view	not done
10	Garbage Collection	view	not done
11	Manipulators	view	not done
12	Finally block	view	not done
13	Final Variable	view	not done
14	Exception	view	not done
15	Error vs Exception	view	not done
16	Exception Handling	view	not done
17	Finalize method in JAVA	view	not done
18	Tokens	view	not done
19	Ternary Operator	view	not done
20	Enum	view	not done
21	Design Patterns	view	not done
22	Using struct vs class	view	not done
23	Cohesion vs Coupling	view	not done

Is it possible for a class to inherit the constructor of its base class ? 
super keyword
order of constructor and destructor calling sequence in case of various inheritance schemes.
Singleton pattern example.

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Links and resources for strengthening the concepts of Object Oriented Programming [Java and C++]