This document is a beginner's guide to object-oriented programming (OOP) in C++, covering essential concepts such as pointers, structures, classes, encapsulation, inheritance, and polymorphism. It includes code examples demonstrating the use of these concepts along with explanations of functions, call by value/reference, operator overloading, and file handling. Overall, it serves as an introduction to OOP principles and their application in C++.

1. Beginner’s Guide to OOP
No oops in OOP

2. Introduction
Muzammil Nawaz Asad Ali

3. Contents
 Pointers
 Structures
 Objects and Classes
 Conversion between basic and user-defined data types
 Functions and Types
 Encapsulation
 Inheritance
 Polymorphism
 Unary and Binary Operator’s Overloading
 File Handling in C++

4. Clarification

5. Pointers
 A pointer is a variable that stores the memory address as its value.
 A pointer variable points to a data type (like int or string) of the same
type, and is created with the * operator. The address of the variable you're
working with is assigned to the pointer:
For Example:
 string food = "Pizza"; // A food variable of type string
 string* ptr = &food; //A pointer variable, with the name ptr, that stores the
address of food

6. Why would one want to store Address?

7. Let’s See Code
 #include<iostream>
 #include<conio.h>
 using namespace std;
 void sum(int m, int n);
 int main(){
 int m = 10;
 int n = 2
 sum(m,n);
 cout<<m;

 }
 void sum(int m, int n){
 m= m+n;
 }

8. Output
5+6 = 11 ?

9. To overcome this issue
 We make a pointer that holds the address of a variable
 Any Changes in a reference variable are non-volatile
 There are no way of passing a variable "by reference" to a function. That's where
you have to use pointers

10. Code with Pointers

11. Structures
 We often come around situations where we need to store a group of data whether
of similar data types or non-similar data types. We have seen Arrays in C++ which
are used to store set of data of similar data types
 A structure is a user-defined data type in C/C++. A structure creates a data type
that can be used to group items of possibly different types into a single type.

12. Code Example

13. OOP
 Class and Objects
 Encapsulation
 Polymorphism
 Inheritance

14. (OOP)
Objects and Classes
A class in C++ is a user-defined type or data structure declared with keyword class
that has data and functions as its members whose access is governed by the three
access specifiers private, protected or public. By default access to members of a C++
class is private.
Class is a blueprint, Object is physically present in memory

15. Everything_around_you == Object

16. Example
 #include<iostream>
 #include<conio.h>
 using namespace std;
 class MyClass{
 public:
 int myNum;
 string myString;

 };
 int main(){

 MyClass object;
 object.myNum = 73;
 object.myString = "Muzzamil";
 cout<<object.myString<<", "<<object.myNum;
 }

17. Accessed Object values

18. Functions and Types
 A function is a block of code which only runs when it is called.
 You can pass data, known as parameters, into a function
 C++ provides some pre-defined functions, such as main(), which is
used to execute code. But you can also create your own functions to
perform certain actions.
 Syntax
 void myFunction() {
// code to be executed
}
 void means that the function does not have a return value.

19. Example

20. Types of Function
 Return types can be bool, char, string, int, float even an object
Int type
Bool type
Both are Pass-by Value methods

21. Pass by Value vs. Pass by Reference
 In call by reference the actual value that is passed as argument is changed after
performing some operation on it. When call by reference is used, it creates a copy
of the reference of that variable into the stack section in memory
 The call by reference is mainly used when we want to change the value of the
passed argument into the invoker function.

22. Example (pass by reference)

23. Encapsulation #include<iostream>
#include<conio.h>
using namespace std;

24. Why Encapsulation?
 Consider a real life example of encapsulation, in a company there are different
sections like the accounts section, finance section, sales section etc. The finance
section handles all the financial transactions and keep records of all the data
related to finance. Similarly the sales section handles all the sales related activities
and keep records of all the sales. Now there may arise a situation when for some
reason an official from finance section needs all the data about sales in a particular
month. In this case, he is not allowed to directly access the data of sales section. He
will first have to contact some other officer in the sales section and then request
him to give the particular data. This is what encapsulation is. Here the data of sales
section and the employees that can manipulate them are wrapped under a single
name “sales section”.

25. Inheritance

27. Example (Single) {All public methods}

28. Example(Multi Inheritance)

29. Multiple Inheritance in
C++ only

30. Polymorphism
 Many Shapes/Forms

31. Function/Method Overload
Function having same name different parameters
Judged at compile time.

32. Function Override
 Function having same name, same parameters different classes
 Judged at Runtime.

34. Now No oops in OOP

35. Reality is often disappointing

36. Unary and Binary Operator’s Overloading
Unary = Single Argument(operation), works with one class’ object only

37. Binary Operator’s
 A single argument(Operator) but two objects as operands

39. File Handling
 Files are important as they store our data
 #include<fstream>
 Creating a file: open()
 Reading data: read()
 Writing new Data: write()
 Closing a file (crucial): close()

40. Create a file

41. Read a file

42. Write on a File

45. Thank You ;)
17sw73@students.muet.edu.pk 17sw45@students.muet.edu.pk