1.
W hat is OOP?
Object-oriented programming (OOP)
is a programming paradigm that uses "objects" – data structures
consisting of data fields and methods together with their interactions – to
design applications and computer programs. Programming techniques may include
features such as data abstraction, encapsulation, modularity, polymorphism, and
inheritance. It was not commonly used in mainstream software application
development until the early 1990s.[citation needed] Many modern programming
languages now support OOP.
An object-oriented program may
thus be viewed as a collection of interacting objects, as opposed to the
conventional model, in which a program is seen as a list of tasks (subroutines)
to perform. In OOP, each object is capable of receiving messages, processing
data, and sending messages to other objects and can be viewed as an independent
'machine' with a distinct role or responsibility. The actions (or
"operators") on these objects are closely associated with the object.
For example, the data structures tend to 'carry their own operators around with
them' (or at least "inherit" them from a similar object or class).
One of the principal advantages
of object-oriented programming techniques over procedural programming
techniques is that they enable programmers to create modules that do not need
to be changed when a new type of object is added. A programmer can simply
create a new object that inherits many of its features from existing objects.
This makes object-oriented programs easier to modify.
2.
Explain objects and class with an example.
Objects:
Object is the basic unit of
object-oriented programming. Objects are identified by its unique name. An
object represents a particular instance of a class. There can be more than one
instance of an object. Each instance of an object can hold its own relevant
data.
An Object is a collection
of data members and associated member functions also known as methods.
Classes:
Classes are
data types based on which objects are created. Objects with similar properties
and methods are grouped together to form a Class. Thus a Class represents a set
of individual objects. Characteristics of an object are represented in a class
as Properties. The actions that can be performed by objects become functions of
the class and is referred to as Methods.
For example
consider we have a Class of Cars under which Santro Xing, Alto and WaganR
represents individual Objects. In this context each Car Object will have its
own, Model, Year of Manufacture, Colour, Top Speed, Engine Power etc., which
form Properties of the Car class and the associated actions i.e., object
functions like Start, Move, Stop form the Methods of Car Class.
No memory is
allocated when a class is created. Memory is allocated only when an object is
created, i.e., when an instance of a class is created.
Differences between struct in C and classes in C++
In C++, a structure is a class
defined with the struct keyword.[1] Its members and base classes are public by
default. A class defined with the class keyword has private members and base
classes by default. This is the only difference between structs and classes in
C++.
Classes are declared with the
class or struct keyword. Declaration of members are placed within this
declaration.
struct person
{
string name;
int age;
};
class person
{
public:
string name;
int age;
};
Example of
class and object:-
#include <iostream>
#include <string>
class person
{
public:
string name;
int age;
};
int main ()
{
person a, b;
a.name = "Calvin";
b.name = "Hobbes";
a.age = 30;
b.age = 20;
cout << a.name << ": "
<< a.age << endl;
cout << b.name << ": "
<< b.age << endl;
return 0;
}
Executing the above code will
output
Calvin: 30
Hobbes: 20
3. Explain
following
1.)
Encapsulation:- Encapsulation is the process of combining
data and functions into a single unit called class. Using the method of
encapsulation, the programmer cannot directly access the data. Data is only
accessible through the functions present inside the class. Data encapsulation
led to the important concept of data hiding. Data hiding is the implementation
details of a class that are hidden from the user. The concept of restricted
access led programmers to write specialized functions or methods for performing
the operations on hidden members of the class. Attention must be paid to ensure
that the class is designed properly.
2.)
Data Hiding:- Related to the idea of encapsulation is the
concept of data hiding. Encapsulation hides the data from other classes and
functions in other classes. This makes programs more reliable, since publishing
a specific interface to an object prevents inadvertent access to data in ways
that were not designed or accounted for. In C++, the access to an object, and
its encapsulated data and functions is treated very carefully, by the use of
keywords private, protected, and public.
3.)
Data
Abstraction:- Data abstraction is the result of defining classes with
emphasis on the similarities of its objects and ignoring their differences. A
good abstraction is one that emphasizes details that are significant to us and
suppresses details that are not important. A class is an abstraction. Thus, an
abstraction focuses on the outside view of the object and clearly separates its
essential behavior from the internal implementation details.
1.Emphasizes similarity of objects and ignore their differences
2.Good abstraction emphasizes significant details and ignores unimportant details.
3.Class is abstraction
4. Focuses on outside view of object only.
1.Emphasizes similarity of objects and ignore their differences
2.Good abstraction emphasizes significant details and ignores unimportant details.
3.Class is abstraction
4. Focuses on outside view of object only.
4.)
Reusability :- This term refers to the ability for
multiple programmers to use the same written and debugged existing class of
data. This is a time saving device and adds code efficiency to the language.
Additionally, the programmer can incorporate new features to the existing
class, further developing the application and allowing users to achieve
increased performance. This time saving feature optimizes code, helps in gaining
secured applications and facilitates easier maintenance on the application.
The implementation of each of the above object-oriented programming features for C++ will be highlighted in later sections.
The implementation of each of the above object-oriented programming features for C++ will be highlighted in later sections.
5.)
Dynamic Binding
:- Binding refers to the linking of a function call to the code to be
executed in response to the call. Dynamic Binding means that the code
associated with the given function call is not known until the time of call at
runtime. A Function call associated with a polymorphic reference depends on
dynamic type of that reference. Dynamic binding has two forms, static and
dynamic. Statically-typed dynamic
binding is found in languages such as C++ (virtual functions) . It is not known which function will be called
for a virtual function at run-time because a derived class may override the
function, in which case the overriding function must be called. Statically determining all possibilities of
usage is undecidable. When the complete
program is compiled, all such functions are resolved (statically) for actual
objects.
Inheritance is the process by
which new classes called derived classes are created from existing classes
called base classes. The derived classes have all the features of the base class
and the programmer can choose to add new features specific to the newly created
derived class.
For example, a programmer can create a base class named fruit and define derived classes as mango, orange, banana, etc. Each of these derived classes, (mango, orange, banana, etc.) has all the features of the base class (fruit) with additional attributes or features specific to these newly created derived classes. Mango would have its own defined features, orange would have its own defined features, banana would have its own defined features, etc.
For example, a programmer can create a base class named fruit and define derived classes as mango, orange, banana, etc. Each of these derived classes, (mango, orange, banana, etc.) has all the features of the base class (fruit) with additional attributes or features specific to these newly created derived classes. Mango would have its own defined features, orange would have its own defined features, banana would have its own defined features, etc.
#include <iostream.h>
class fruit
{
public:
void fruit_color(char *color)
{
Cout<<”Fruit color
is:”<<color;
}
};
class mango : public fruit
{
};
int main()
{
Clrscr();
mango obj;
obj.fruit_color(“yellow”);
getch();
}
This concept of Inheritance
leads to the concept of polymorphism.
Features or Advantages of Inheritance:
·
Reusability
·
Saves Time and Effort
·
Increases Program Structure which results in
greater reliability. Polymorphism
5. What is Polymorphism? Explain
Operator Overloading and function overloading.
Polymorphism:- Polymorphism is the ability to use an
operator or function in different ways. Polymorphism gives different meanings
or functions to the operators or functions. Poly, referring to many, signifies
the many uses of these operators and functions. A single function usage or an
operator functioning in many ways can be called polymorphism. Polymorphism
refers to codes, operations or objects that behave differently in different
contexts.
Features
and Advantages of the concept of Polymorphism:
·
Applications are Easily Extendable
·
Helps in reusability of code.
·
Provides easier maintenance of applications.
·
Helps in achieving robustness in applications.
Types of
Polymorphism:
C++ provides three different
types of polymorphism.
·
Virtual functions
·
Function name overloading
·
Operator overloading
Operator
Overloading:- One of the nice
features of C++ is that you can give special meanings to operators, when they
are used with user-defined classes. This is called operator overloading. You
can implement C++ operator overloads by providing special member-functions on
your classes that follow a particular naming convention. For example, to
overload the + operator for your class, you would provide a member-function
named operator+ on your class.
The
following set of operators is commonly overloaded for user-defined classes:
·
= (assignment operator)
·
+ - * (binary arithmetic operators)
·
+= -= *= (compound assignment operators)
·
== != (comparison operators)
Function
Overloading: In function overloading, the function is said to be overloaded
when same name is given to different functions. However, the functions will
differ at least in any one of the these. The number of parameters, the data
type of parameters, the order of appearance these three together are referred
to as the function signature. While overloading a function, the return types of
the function need not differ.
6.Give
the benefits of Object Oriented Programming.
1. Testability/Increased
Quality (automated testing can increase speed of testing and increase quality)
2. Code
re-use (Polymorphism, Generics, Interfaces)
3. Code
extensibility
4. Catch
errors at compile time rather than at runtime.
5. Maintainability:
If designed correctly, any tier of the application can be replaced by another
that implements the correct interface(s), and the application will still work
(can use multiple user interfaces, can swap out data providers, etc.).
6. Reduces
large problems to smaller, more manageable ones.
7. Fits
the way the real world works. It is easy to map a real world problem to a
solution in OO code.
7.Give
the features of Object Oriented Programming language.
·
Data encapsulation
·
Data abstraction
·
Inheritance
·
Polymorphism
·
Dynamic or runtime binding
·
Reusability
·
Information hiding.
