Concept about C++:C++ is an enhanced version of the C language. C++ includes everything that is part of C language and adds support for object oriented programming (OOP). With very few, very major exceptions, C++ is a superset of C.

A look at procedure oriented programming: Conventional programming, using high level languages such as COBOL, FORTRAN and C, is commonly known as procedure-oriented programming (POP). In the procedure-oriented approach, the problem is viewed as a sequence of things to be done such as reading, calculating and printing. A number of functions are written to accomplish these tasks. The primary focus is on functions. A typical program structure for procedural programming is shown in Fig. .

Figure: Typical structure of procedure-oriented programs

Main Program

Function-1 Function-2 Function-3

Function-5

Function-8Function-7Function-6

Function-4

Main characteristics of procedure-oriented programming are: Emphasis is on doing things (algorithms).Large programs are divided into smaller programs known as functions.Most of the functions share global data.Data move openly around the system from function to function.Functions transform data from one form to another.

Employs top-down approach in program design.In top down approach, first we are designing the main module (i.e main function) and then we will design all other sub modules.

Object-Oriented Programming paradigm:The major motivating factor in the invention of object-oriented approach is to remove some of the flows encountered in the procedural approach. OOP treats data as a critical element in the program development and does not allow it to flow freely around the system. It ties data more closely to the functions that operate on it, and protects it from accidental modification from outside functions.

OOP allows decomposition of a problem into a number of entities called object and then builds data and functions around these objects. The data of an object can be accessed only by the functions associated with that object. However, functions of one object can access the functions of other objects.  

Object A Object B

Communication

Object C

Figure: Organization of data and functions in OOP

Data

Function

Data

Function

Function

Data

Striking features of object-oriented programming are:Emphasis is on data rather than procedure.Programs are divided into what are known as objects.Data structures are designed such that they characterize the objects.Functions that operate on the data of an object are tied together in the data structure.

Data is hidden and cannot be accessed by external functions.Objects may communicate with each other through functions.New data and functions can be easily added whenever necessary.Follow bottom-up approach in program design.In bottom up approach, first we design all the sub modules related to application then we design main module.

C++ Console I/O:In C programming language, we are using printf() function for output operation and scanf() function for input operation. But in C++, cout<< is using for output operation and cin>> function is using for input operation. “<<” operator is called insertion or put to operator . “>>” operator is called extraction or get from operator.

Example:cout<<”Object-Oriented Programming ”;cout<<100.99; int num;cin>>num; 

Program:  #include<iostream.h>//C++ console i/o operatorint main(){int i, j;double d;i=10;j=20;d= 99.101;cout<<"Here are some values:";

cout<<i;cout<<' ';cout<<j;cout<<' ';cout<<d;return 0;}Output:Here are some values- 10 20 99.101Assignment:Write a program that uses C++ style I/O and produce the output as: 6.62 9.34 99 110

C++ Comments In C++, we can include comments in our program two different ways such as-For multiline comments, began a comment with /* and end it with */ For single line comments, began a comment with // and stop at the end of the line.

Program: #include<iostream.h>//Comments programint main(){char ch; //this is a single line comment/* this is amulti line comment*/cout<<"Enter keys, x to stop.\n";

do{cout<<":";cin>>ch;}while(ch!='x');return 0;}output:enter keys, x to stop:dgsdds sdsdx 

  Classes and Objects

Limitation of C structures and benefits of C++ classes: 1) Suppose student is a structure name in C language can be define as struct student{ Int roll_number;float marks;}; main(){struct student C1,C2,C3; // C struct type variable declaration. C3=C1+C2; // it is not possible to add two string type variable in C language. }

it is not possible to add two structure type variable in C language. But in C++, we can add two class type objects like data type variable as shown bellow. This facility in C++ called Operator Overloading.  class semp{ Int roll_number;float marks;--------------};  

main(){semp A1,A2,A3; // class type object declaration. A3=A1+A2; // it is possible to add two object in C++ language. }

2) C++ class provides data hiding facility. C++ class can declare some of its members as private so that they cannot be accessed directly by the external functions. This is called data hiding facility.But in C structure, datas are declared only as public by default. So C structure cannot provide data hiding facility.  3) C++ support inheritance facility. Inheritance is a mechanism by which one type can inherit characteristics from other types, is also supported by C++.  4) In C, we need to use struct keywords for structure type variable declaration. But in C++, we no need to use class keywords for class type object declaration.