1. Concepts and Basics of C++ Programming
CSE 202

2. Object-Orientation A thinking methodology Everything is an object.
Any system is composed of objects (a system is also an object).
The evolution and development of a system is caused by the interactions of the objects inside/outside a system.

3. Everything is an object
A student, a professor
A desk, a chair, a classroom, a building
A university, a city, a country
The world, the universe
A subject such as CS, IS, Math, History, …

4. Reading and Writing Data

5. Reading and Writing Data
Two operators are introduced in c++ i.e. cout and cin.
Cout is a predefined object and represents the standard output stream and this output stream represents the screen. Cout, equires iostream file
E.g. cout<<“ I love india”;
cout will display this string as such on screen.

6. << is called insertion or put to operator.
It is also called bit-wise left -shift operator
if string is variable then cout can be used to display the contents of string.
E.g. cout<< string;
cin is used to read the data.
cin>>a;
>> is called extraction operator.

7. The cout Object Displays output on the computer screen
You use the stream insertion operator << to send output to cout:
cout <<"Programming is fun!";

8. The cout Object Can be used to send more than one item to cout:
cout << "Hello " << "there!";
Or:
cout << "Hello ";
cout << "there!";

9. The cout Object
This produces one line of output: cout << "Programming is "; cout << "fun!";

10. The cin Object Standard input object Like cout, requires iostream file
Used to read input from keyboard
Information retrieved from cin with >>
Input is stored in one or more variables

11. The cin Object
cin converts data to the type that matches the variable:
int height;
cout << "How tall is the room? ";
cin >> height;

12. The cin Object Can be used to input more than one value:
cin >> height >> width;
Multiple values from keyboard must be separated by spaces
Order is important: first value entered goes to first variable, etc.

13. Reading Strings with cin
Can be used to read in a string
Must first declare an array to hold characters in string:
char myName[21];
nyName is name of array, 21 is the number of characters that can be stored (the size of the array), including the NULL character at the end
Can be used with cin to assign a value:
cin >> myName;

14. Class
A class is a user define data type which holds both data and function.
The data included in the class i.e the internal data is called data member and the functions included is called the member function.
These member functions can manipulate the internal data of the class

15. Object Is an instant of a class.
In terms of variables, class would be the type and an object would be a variable.

16. Creating Classes in C++
A class definition begins with the keyword class.
The body of the class is contained within a set of braces, { } ; (notice the semi-colon).
class class_name { …. };
Any valid identifier
Class body (data member + methods)

17. class classname {
private:
variable declarations;
function declarations;
public:
protected:
} obj1, obj2,…..objN;

18. Class name
Name given to a particular class (any user define name). It can also be called as tag name of the class that act as the type specifier for class using which we can create objects.
The class is specified by keyword “class”

19. Data Members
Data type properties that describe the characteristics of a class.
We can declare any number of data members of any type in a class.
E.g. int x;

20. Member functions
Various operations that can be performed to data members of that class.
We can declare any number of member functions of any type in a class.
E.g. void read();

21. Access Specifiers
Used to specify access rights for the data members and member functions of the class.
Depending upon the access level of a class member, access to it is allowed or denied.
Within the body, the keywords private: and public: specify the access level of the members of the class.
the default is private.
Usually, the data members of a class are declared in the private: section of the class and the member functions are in public: section.

22. class class_name {
private: …
public: };
private members or methods
Public members or methods

23. Private:
only members of that class have accessibility
can be accessed only through member functions of that class i.e by the functions declared inside the class only.
Private members and methods are for internal use only.

24. Public:
Accessible from both inside and outside the class also i.e by the functions declared in the main() program also.
Protected:
Stage between private and public access.
They can be accessed by the member function or friend functions of the class. They are similar to private members in the sense that they cannot be accessed by the non- member functions of the class.

25. Class Example
This class example shows how we can encapsulate (gather) a circle information into one package (unit or class)
No need for others classes to access and retrieve its value directly. The
class methods are responsible for
that only.
class Circle {
private:
double radius;
public:
void setRadius(double r); double getDiameter();
double getArea();
double getCircumference(); };
They are accessible from outside
the class, and they can access the
member (radius)

26. Methods definition
The member function of the class can be defined in two different ways:
Inside the class definition:- The member functions are simple defined inside the class only i.e the body of the function resides inside the range of class only.
2) Outside the class definition: by using scope resolution operator, which specifies that the scope of the function is restricted to the class class_name.
Syntax:- class_name:: function_name

27. Inside the class definition
Eg: class abc {
private:
int rollno;
char name[20];
public:
void getdata()
cout<<“name=“;
cin>>name;
cout<<“rollno=“; cin>>rollno; } void display() { cout<<“name=“<<name; cout<<“rollno=“<<rollno; };

28. Outside the class definition
cin>>name; cout<<“rollno=“; cin>>rollno; } void abc :: display() { cout<<“name and rollno=“; cout<<name<<rollno;
Eg: class abc { private: int rollno; char name[20]; public: void getdata(); void display(); }; void abc :: getdata() cout<<“name=“;

29. INLINE AND NON INLINE MEMBER FUNCTION
A function defined inside the class is by default inline function
A function defined outside the class using scope resolution operation is non-inline function. It can be made inline by using keyword inline before the function definition.
Eg inline void abc::getdata()

30. Declaring objects
Defining objects of class data type is known as class instantiation(instances of class).
When we create objects during that moment , memory is allocated to them.
Ex- class Circle c;

31. class book {
private:
int p; char n[40];
public:
void getdata()
cout<<“enter book price”;
cin>>p;
cout<<“enter book name”;
cin>>n; }
void display(); };
void book ::display() { cout<<“book name=“<<n; cout<<“book price=“<<p; } void main() class book obj; obj.getdata(); obj.display();

32. Accessing class members
Public members of class can be accessed using dot(.) operator with the object name.
Private members of the class are accessed inside the public member functions of class.
Eg: obj.getdata();

33. Thank You!
For any query: