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C++ Chapter 4

Q.  Explain the terms:
(i)                 Dynamic Biding
(ii)               Message Passing


Ans. Dynamic Binding: - Dynamic Binding is also known as late binding means that the code associated with a procedure call is not known until the time of the call at run time. Binding refers to the linking of code with procedure call at the time of execution in the response of call. Dynamic binding is associated with ‘polymorphism’ and ‘inheritance’, for ex. in a polymorphism program a function/procedure call associated with a polymorphic reference depends on the dynamic type of that reference.

Message Passing: - In Object Oriented Programming we create class that define objects and their behaviors, create objects of classes, and establishing the communication between among objects. In OOP we can make the number of objects and these objects can communicate with each other. These objects communicate with each other by sending and receiving information to each other in the same as peoples communicate with each other. A message is a request for an object to execute of a procedure, or calling a function. A message passing involves specifying the name of the object, the name of the function (that is also known as message) and the information to be sent ex.student.marks (course) student is an object here, marks is a message and course is an information.

Q (a) Differentiate between the following: July 05
(a)   Object & Classes?
(b)   Data Abstraction & Data Hiding?
(c)    Data Abstraction & Data encapsulation?
(d)   Inheritance and polymorphism?

Ans. (a) Object & Class
Object is a run-time entity, which may represent a person, a place, a table of data, or anything. Object contains data and code to manipulate the data. The problem of Object-Oriented Programming is solved in term of objects and communication between them. The names of objects are choose in such way that they looks very closely to real world objects. When an object is created it take place in memory and has a unique address like a structure in C. when a program is execute, objects interact with each other in the form of messages. Objects can interact without having the knowledge of data and code of each other.

Class is a user-defined data type, or a class is a logical entity which contains the set of attributes and behavior, or a class is a collection of objects of similar type. Object is variable of type class. After creating a class we can make any number of objects belonging to that class. Each object is associated with the data of type class with which they are crated.

(b) Data Abstraction & Data Hiding
Abstraction refers to representing of essential features without including the background detail or explanation. Class uses the concept of abstraction and defines the attributes (variables) and functions (procedures), function make the operation on these attributes. Classes use the concept of data abstraction and also known as ‘Abstract Data Types’ (ADT)
 The functions provides the interface between the object’s data and the program, we can access data from class only through objects. This insulation of the data from direct access by the program is called data hiding.

(c) Data Abstraction & Data encapsulation
The wrapping of data and functions into a single unit is called encapsulation, or the wrapping of data and functions into a class is called encapsulation. Data encapsulation is a most important feature of class. It means the data encapsulate in the class is not accessible by outside world and only those function which are wrapped in the class can access it. Class encapsulates the properties of objects that are to be created.
Abstraction refers to representing of essential features without including the background detail or explanation. Class uses the concept of abstraction and defines the attributes (variables) and functions (procedures), function make the operation on these attributes. Classes use the concept of data abstraction and also known as ‘Abstract Data Types’ (ADT)


(d) Inheritance and polymorphism
The concept of inheritance provides the facility of code reusability. Inheritance means the object of one class inherit the properties of another class object. It allows the programmer to use the code again which already has been tested and debugged without retyping same again. It means we can add additional features to an existing class without modifying it. This is achieved by to deriving a new class from existing one. This new class has the combined features of both classes.
Polymorphism means ability to take more than one form it means one name having multiple forms. Polymorphism is one of the most important characteristic of OOP. Concept of ‘polymorphism’ is used in function overloading and in operator overloading for ex. if a class has more than one function with same name and different parameters is called function overloading, which refers to polymorphism. There are two types of Polymorphism ‘Compile Time Polymorphism’ and ‘Run Time Polymorphism’.

Q. Write a program in C++ to find the greatest and the second greatest from a list of numbers.

Ans. #include<iostream.h>
#include<conio.h>
class abc
{
public:
int arr[100],no,i,max,smax,temp;
void find();
};
void abc::find()
{
i=-1,max=smax=0;
cout<<"\n Enter Number or -0 to exit :: ";
cin>>no;
while(no!=-0)
{
i++;
if(i==100)
{
cout<<"\n Over Flow Enter -0 to Exit  ";
}
else
{
arr[i]=no;
if(arr[i]>=max)
{
temp=max;
max=arr[i];
smax=temp;
}
else if(arr[i]<max&&arr[i]>=smax)
smax=arr[i];
cout<<"\n Enter Number or -0 to exit :: ";
cin>>no;
}
}
cout<<"\n Greatest Number = "<<max;
cout<<"\n Second Greatest Number = "<<smax;
}
void main()
{
clrscr();
abc obj;
obj.find();
getch();
}

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