Chapter 2 – Object Oriented Programming in C++ NCERT Solutions for Class 12 Computer Science (C++)

NCERT Solutions for Class 12 Computer Science (C++) Chapter 2 – Object-Oriented Programming in C++ – Free PDF download

NCERT Solutions for Class 12 Computer Science

TOPIC – 1

Object Oriented Programming : Introduction

Short Answer Type Questions-I    [2 marks each]

Question 1:
Differentiate between data abstraction and data hiding.    [Delhi, 2015]
Answer:
Data hiding can be defined as the mechanism of hiding the data of a class from the outside world. This is done to protect the data from any accidental or intentional access. Data hiding is achieved by making the members of the class private.
Data abstraction refers to, providing only essential information to’ the outside world and hiding their background details.
Members defined with a public label are accessible to all parts of the program. The data abstraction view of a type is defined by its public members.

Question 2:
How encapsulation and abstraction are implemented in C++ language ? Explain with an example.    [CBSE SQP 2015]
Answer:
Abstraction refers to the act of representing essential features without including the back-ground details or explanations.
Encapsulation is wrapping up of data and function together in a single unit.
We can say that encapsulation is way of achieving abstraction. Both these concepts are implemented in C++ in the form of a class. In a class data and function members are wrapped together. Only essential features are shown to the outside world in the form of member functions with public mode of accessibility. [1]
Example:     [1]

class Rectangle  {  int L, B;  public: void Input()   {       cin>>L>>B;   }  void Output()  {  Cout<<L<<B;  }  };

In this example:
Data and member functions are together encapsulated
Only Input ( ) and Output ( ) functions are visible outside the class which can only can be accessed outside the class using objects of the same class – Abstraction

Question 3:
Explain data hiding with an example. [CBSE Comptt., 2014]
Answer:
Data Hiding
Data Hiding is the mechanism where the details of the class are hidden from the user.
The user can perform only a restricted set of operations in the hidden member of the class For example,
In order to make the design and maintenance of a car reasonable the complexity of equipment is divided into modules with particular interfaces hiding design decisions.
General Form:

class classname  {  private: datatype data;     public:        Member functions,-"  };  main()  {  classname objectnamel, objectname2

.........;  {  Example :

class Square

{  private  int Num;  public:  void Get() {  cout<<"Enter Number:";  cin>>Num;  }  void Display!) { cout<<"Square Is:"<<Num*Num;  }  };  void main()  {  Square Obj;  Obj.Get();  Obj.Display ();    [1]  getch()  }

Question 4:
What do you understand by data encapsulation and Data hiding ?
Also, give a suitable C++ code to illustrate both.    [CBSE SQP 2013]
Answer:
Data hiding is a property of OOP by which the crucial data of an object is made hidden from the rest of the program or outside the world. [1]
Encapsulation refers to the wrapping of data and associated functions together under a unit class. [1]

// Program for hiding & Encapsulation  #include <iostream.h>  class Adder {    // Encapsulation  public :  Adder (int i = 0)  { total = i;}  void addNum (int Number)  { total + = Number;  }  int getTotal ( )  { return total;  }  private : int total ;  //Data Hiding }; int main ( ) { Adder a; a . addNum (10); a . addNum (20); a . addNum (30); cout << "Total :<<a.getTotal ( ) < < endl; return 0 ; }

Question 5:
Write the output of the following C++ program code:    [Delhi, 2015]

class Eval { char Level;  int Point; Public : Eval () { Level = "E" ; Point = 0; } void Sink (int L) { Level - = L; } void Float (int L) { Level + = L; Point ++; } void Show ( ) { cout<<Level<<"#"<<Point<<endl; } }; void main ( ) { Eval E; E. Sink (3) ; E. Show ( ); E. Float (7); E. Show ( ); E. Sink (2) ; E. Show ( ); }

Answer:
B#0
I#1
G#1
(1 Mark for each correct line of output)
Note:
•  Deduct 1/2 Mark for not considering any or all end/(s) at proper place(s)
•  Deduct 1/2 Mark for not writing any for all symbol(s) [CBSE Marking Scheme 2015]

Question 6:
Observe the following program carefully and attempt the given questions :

#include<iostream.h>
#include<cono.h>
#include<stdlib,h>
void main()
clrscr();
randomize();
char courses![ ] [10]={“M.Tech”.”MCA”, “MBA”,”B.Tech”};
int ch;
for(int i= l;i<=3;i++)
{
ch=random(i)+1;
cout<<courses[ch]<<“ ;
}
getch () ;
}

(i) Out of all the four courses stored in the variable courses, which course will never be displayed in the output and which course will always be displayed at first in the output ?
(ii) Mention the minimum and the maximum value assigned to the variable ch ? [CBSE SQP 2016]
Answer:
(i) M. Tech will never be displayed in the output.
MCA will always be displayed at first in the output.
(ii) Minimum value of ch=l
Maximum value of ch=3
(1 Mark for each correct answer)
Note:
• Deduct 1/2  Mark for writing any additional option. [CBSE Marking Scheme 2016]

Question 7:
Study the following program and select the possible output(s) from the options (i) to (iv) following it. Also, write the maximum and the minimum values that can be assigned to the variable VAL.
Note:
— Assume all required header files are already being included in the program.
— random(n) function generates an integer between 0 and n -1.    [O.D, 2015]

void main ()  {  randomize ()    ;  int VAL;  VAL = random (3) + 2;  chart GUESS [    ]    = "ABCDEFGHIJK"  ;    for (int I = 1; I < = VAL;  I ++)  {  for (int J = VAL; J < = 7; J ++)  Cout<<GUESS [J] ;  cout<<endl;  }

Answer:
(ii) and (iii)
Min Value of VAL = 2
Max Value of VAL. = 4
(1/2 CA Mark for writing option (ii))
(1/2 Mark for writing option (iii))
Note:
• Deduct 1/2 mark for ivriting each additional option along with both correct options:
(1/2 Mark for writing correct Minimum value of VAL)
(1/2 Mark for writing correct Maximum value of VAL) [CBSE Marking Scheme 2015]

Question 8:
Rewrite the following program after removing the syntax errors (if any). Under line each correction.    [O.D, 2012]

#include <iostream.h> Class Item { long IId, Qty;  public : void Purchase {cin>>IId>>Qty;}  void sale () { cout<<setw (5)<< IId<<" Old :"<Qty  <<endl; cout<<"New :" <<Qty<<endl; } }; void main () { Item I; Purchase (); I. Sale () ; I. Sale () }

Answer:

#include<iostream.h> #include<iomanip.h>  class Item  { long IId, Qty;  public : void purchase()  {cin>>IId>>Qty;}  void sale() { cout<<setw(5)<<IId<<"Old"<<Qty<<endl;  cout<< "New    Qty<<endl; } }; void main( ) { Item I ; I. purchase( ); // Object missing  I. sale ( ) ; I. sale( ); //; is missing } (1/4 mark for each correction)

Question 9:
Rewrite the following program after removing the syntax errors (if any). Underline each correction.    [Delhi, 2012]

# include <iostream.h>  class book { long Bid, Qty;  public : void purchase () {cin>>BID>>Qty;}  void sale ( ) { cout<<setw<<BId<<"Old:"<<Qty<<en  dl; cout<<"New; "<<—Qty<<endl; } }; void main () { Book B; B. Purchase();  sale (); B. Sale () }

Answer:

#include<iomanip.h> #include<iostream.h>  class Book  { long Bid, Qty;  public: void purchase()(cin>>Bld>>Qty;)  void sale( ) { cout < < setw(5) < < Bld < < "0ld " < < Qty < < e n dl; cout<"New:"<<—Qty<<endl; } } ; void main () { Book B; B. purchase (); B. sale(); } (1/2 mark for each correction) [CBSE Marking Scheme 2012]

Question 10:
Answer the questions (i) and (ii) after going through the following class:    [O. D, 2012]

class Travel { int PlaceCode; char Place [20] ;  float Charges;  public : Travel ( )    //Function 1 { PlaceCode = 1; strcpy (Place, "DELHI"); Charges =1000; } void TravelPlan (float C) //Function 2 { cout<<PlaceCode<< ":" <<Place<< ":" <<Charges<<endl;

}  - Travel ( )   //Function 3 { cout<<"Travel Plan Cancelled"<< endl; } Travel (int PC, char P [], float C)                          // Function 4 { PlaceCode = PC; strcpy (Place, P); Charges = C; } } ;

(i) In Object Oriented Programming, what are Function 1 and Function 4 combinely referred to as ?
(ii) In Object Oriented Programming which concept is illustrated by Function 3? When is this function called/invoked ?
Answer:
The concept demonstrated is constructor over-loading:
(i)  Function 1 and Function 4 are called overloaded Constructor of the Class Travel.
(ii) Function 3 is Destructor of Class Travel.
The destructors are called automatically
when the objects are destroyed.    [2]

Short Answer Type Questions-II (3 marks each)

Question 1:
Write any four important characteristics of object Oriented Programming ? Give example of any one of the characteristics using C++. [O.D, 2016]
Answer:

Question 2:
Find the output of the following C++ program [CBSE SQP 2015]

#include<iostream.h> #include<conio.h> #include<ctype.h>  class Class  { int Cno,total;  char section; public: Class(int no=l) { Cno=no;  section="A";  total=30; } void admission(int c=20) { section++; total+=c; } void ClassShow () { cout<<Cno<<":"<<section<<":"<<total< endl; } }; void main () { Class C1 (5),C2; Cl.admission(25) Cl.ClassShow(); C2.admission() ; Cl.admission(30) C2.ClassShow(); Cl.ClassShow(); }

Answer:
5 : B : 55 [1]
1: B : 50 [1]
5 : C : 85 [1]

Question 3:
Obtain the output of the following C+ + program, which will appear on the screen after its execution.
Important Note:
• All the desired header files are already included in the code, which are required to run the code,

class Game  { int Level, Score;  char Type;  public: Game (char GType="p") {Level=1; Score=0; Type= GType;}  void Play (int GS);  void Change ();  void Show() { cout<<Type<<"@"<<Level<<endl;  cout<<Score<<endl; } } ; void main ()  { Game A ("G"), B; B. Show (); A. Play (11); A. Change (); B. Play (25); A. Show (); B. Show (); } void Game:    : Change() { Type=(Type== "P")?"G" :"P"; } void Game: :Play(int GS) { Score+=GS;  if(Score>=30) Level=3; else if (Score>=20) Level=2;  else Level=l; }        [O.D, 2014]

Answer:

P@1
0
P@1
11
P@2
25
(1/2 mark for each correct line)

Question 4:
Obtain the output of the following C+ + program, which will appear on the screen after its execution.
Important Note:
• All the desired header files are already included in the code, which are required to run the code,

class Player  { int Score, Level;  char Game; public: Player (char GGame="A") {Score=0; Level=1; Game =GGame;}  void Start (int SC);  void Next ();  void Disp () { cout <<Game<<"@"<<Level <<endl;  cout <<Score<<endl; } }; void main () { Player P,Q ("B"); P. Disp (); Q. Start (75); Q. Next (); P. Start (120); Q. DispO ; P.Disp (); } void Player : : Next () { Game = (Game =="A")?"B":"A" ; } void Player : : Start (int SC) { Score+=SC; If (Score>=100) Level=3; else if (Score>=50) Level=2;  else Level=1; }    [O.D, 2014]

Answer:

A@1 0
A@2
75
A@3
120    [3]

Question 5:
Observe the following C++ code carefully and obtain the output, which will appear on the screen after execution of it.

#include <iostream.h>  class Mausam  { int city, Temp, Humidity;  public : Mausam (int C = 1) {City = C; Temp =  10; Humidity = 63;};  void Sun (int T) {Temp + = T;};  void Rain (int H) {Humidity +=H;};  void Checkout ( ) { cout<<City<<":"<<Temp<< "&" <<Humidity  <<"%"<<endl; } } ; void main ( ) { Mausam M, N(2); M. Sun (5); M. Checkout ( ); N.  Rain (10); N.Sun (2)    ; N.Checkout ( ); M.Rain (15)    ; M.Checkout ( ) ; }    [O.D, 2013]

Answer:
Output:
1:1:15% [1]
2:2:12% [1]
3:1:15%  [1]

Question 6:
Observe the following C++ code carefully and obtain the output, which will appear on the screen after execution of it.

# include <iostream.h>  class Aroundus  {  int Place, Humidity, Temp; public:  Aroundus(int p = 2) {  Place = P; Humidity = 60; Temp = 20;  }  void Hot (int T) {  Temp+=T ;  };  void Humid (int H) {  Humidity+=H ;  };  void JustSee ( )  {  cout<<Place<<":"<<Temp<<"&"<<Humidity <<"%"<<endl;  }  };  int main()  {  Aroundus A, B (5) ;  A. Hot (10)    ;  A. JustSee ( )    ;  B. Humid (15)    ;  B. Hot (2)    ;  B. JustSee ( )    ;  A. Humid (5)    ;  A. Justsee ( ) ;    [Delhi, 2013]

Answer:
Output:
2 : 30 & 60%    [1]
5 : 22 & 75%    [1]
2 : 30 & 65%    [1]

Question 7:
Find the output of the following program : [O.D., 2012]

#include <iostream.h>  class METRO  {  int Mno, TripNo, PassengerCount;  public : METRO (int Tmno=l)  {  Mno=Tmno;  TripNo=0;  PassengerCount=0;  }  void Trip (int PC = 20)  { TripNo++; PassengerCount+=PC;}  void StatusShow ()  {cout<<Mno<<" : "<<TripNo<<":"  <<PassengerCount<<endl;}  } ;  int main ()  {  METRO M (5), T;  M.Trip () ;  T.Trip (50) ;  M.StatusShow ();  M.Trip (30)    ;  T.StatusShow ();  M.StatusShow ();  }

Answer:
Output:
5 :1: 20
1 :1 : 50
5 : 2 : 50
(1 mark for each line of output)

Question 8:
Find the output of the following program: [Delhi, 2012]

#include<iostream.h>  class TRAIN  {  int Tno, TripNo, PersonCount;  public :  TRAIN (int Tmno=l) {Tno=Tno; TripNo=0; PersonCount = 0;}  void Trip    (int TC=100)  {TripNo++; PersonCount+=TC;}  void Show ()  {cout<<Tno<<" : "<<Trip’No<<" : "<<Person Count <<endl;}  };  void main ()  {  TRAIN T    (10), N.     N. Trip () ;  T.  Show  () ;  T.  Trip (70)  N.  Trip (40)  N.  Show () ;  T.  Show  () ; }

Answer:
Output:
1202 : 0:0
950 : 2 :140
1202 :1: 70
(1 mark for each line of output)

Question 9:
Write the output of the following C++ progam code:
Note : Assume all required header files are already being included in the program,

class seminar  { char topic [30];  int charges;  public: { strcpy(topic,"Registration");  charges=5000; } seminar(char t [ ] ) { strcpy (topic,t)  charges = 5000; } seminar (intc) { strcpy(topic,"Registration    with Discount") ; charges=5000-c; } void regis(char t [ ], int c) { strcpy(topic, t);  charges=charges+c; } void regis(int c=2000) { charges=charges+c; } void subject(char t [ ],int c) { strcpy(topic,t);  charges=charges+c; } void show ( ) { cout<<topic<<"@<<charges<<endl; } }; void main ( ) { seminar s1,s2(1000),s3("Genetic Mutation") , s4;  s1.show ( );  s2.show ( ); s1.subject("ICT",2000) ;  s1.show ( ); s2.regis("Cyber Crime",2500);  s2.show ( ); s3.regis ( ) ;  s3.show();  s4=s2;  s4.show();  getch(); }    [CBSE SQP, 2016]

Answer:

Registration@5000 Registration with Discount@4000  ICT@7000 Cyber Crime@6500  Genetic Mutation@7000  Cyber Crime@6500

(1/2 mark for each correct output)
Note:
Deduct 1/2 Mark for not considering any “@” symbol [CBSE Marking Scheme, 2016]

Question 10:
Find and write the output of the following C+ + program code:
Note : Assume all required header files are already being included in the program,

class product  {  int PID"  float price;  int Qty;  public:  Product ( ) {PID=100;Price=20;Qty=100;}  void Add(int I, float p)  {  ID=I ;  Price=P;  }  void Alter(int Change,int TQ)  {  Price+=Change;  Qty+=TQ;  }  void Display ( )  {  cout<<"PID:"<<PID<<endl;  cout<<Qty<<"@"<<Price<<endl;  }  };  void main ( )  {  Product P,Q,R;  P. Add(104,50);  Q. Add(201,30) ;  R. Alter(-10,25) ;  P. Display();  Q. Display();  R. Display();  }

Answer:

PID: 100  104@150  PID:29 201 @130 PID:25  100@10

(1/2 mark for each correct line of output)
Note:
• Deduct only 1/2 Mark for not writing any or all.
• Deduct 1/2 Mark for not considering any or all

TOPIC-2

Function Overloading

Short Answer Type Questions-1    [2 marks each]

Question 1:
Answer the questions (i) and (ii) after going through the following class :

class Motor  { int MotorNo. Track;  public : Motor ( );    //Function 1 Motor (int MN) ; //Function 2  Motor (Motor &M); //Function 3  void Allocate ( ) ///Function 4  void Move ( ); //Function 5 } ; void main ( ) { Motor M; }

(i) Out of the following, which of the option is correct for calling Function 2?
Option 1 – Motor N (M);
Option 2 – Motor P (10);
(ii) Name the feature of Object Oriented
Programming, which is illustrated by Function 1, Function 2 and Function 3 combined together.    [Delhi, 2013]
Answer:
(i) Option 2 is correct for calling Function 2. [1]
(ii) Function overloading, i.e., Polymorphism. [1]

Question 2:
Answer the questions (i) and (ii) after going through the following class :

class Race  { int CarNo, Track;  public: Race ( ) ; //Function 1 Race (int CN) ; //Function 2 Race (Race &R);  //Function 3 void Register ( ); //Function 4 void Drive ( ); //Function 5 }; void main ( ) { Race R ; : }

(i) Out of the following, which of the option is correct for calling Function 2?
Option 1 – Race T (30);
Option 2 – Race U (R);
(ii)  Name the feature of Object Oriented
Programming, which is illustrated by Function 1, Function 2 and Function 3 combined together.    [O.D, 2013]
Answer:
(i) Option 1 – Race T (30); is correct since the parameter to T is integer.    [1]
(ii) When Functions – Function 1, Function 2 and Function 3 are combined together, it is referred as constructor overloading, i.e., Polymorphism.    [1]

Question 3:
What is function overloading ? Write an example using C++ to illustrate the concept of function overloading.
Answer:
Function Overloading
In C++, we can declare different functions with same name. This property is called function overloading. Function overloading implements polymorphism.
Example:
# include <iostream.h >
#include < stdlib.h>
#include < conio.h>
#define pi 3.14

class fn    [1] { public: void area(int); //circle  void area(int,int); //rectangle }; void fn : : area(int a) { cout <<"Area of Circle:"<<pi*a*a; } void fn::area (int a, int b) { cout <<"Area of rectangle:"<<a*b; } void main ( ) { int ch;  int a, b, r;  fn obj; cout<<""
l.Area    of Circle n2.Area of Rectangle n3.Exit
:";  cout<<""Enter your Choice:";  cin>>ch;  switch(ch) { case 1:  cin>>r;  obj.area(r); break;    [1] case 2: "cin>>a>>b; obj.area(a,b);  break;  case 3: exit (0); } getch ( ); }

Question 4:
Write the output of the following C++ code. Also, write the name of feature of Objects Oriented Programming used in the following program jointly illustrated by the functions [I] to [IV]

include<iostream.h> void Line ( )    //Function[I] { for(int L=1;L<=80;L++) Cout<<"-"; cout<<endl; } void Line(int N)    //Function[II] { for (int L=1;L<=N;L++) Cout<<"*"; cout<<endl; } void Line (char C, Int N) //Function[III] { for(int L=1;L<=N;L++)  Cout<<C; cout<<endl; } Void Line (int M, int, N)  //Function [IV] { for (int L = 1;L<=N;L++) cout<<M*L; cout<<endl; } void main ( ) { int A=9, B=4 C=3; char K = "#" ; Line (K, B); Line (A,C); }

Answer:
####
91827
Function Overloading
(1/2 Mark for writing each correct output)
(1 Mark for writing the feature, name correctly)

Question 5:
Answer the question (i) and (ii) after going through the following class :

class Test  { int Regno, Max, Min, Score;  public : Test ( )    //Function 1 { Regno =101; Max = 100;    Min=40; Score=75 ; } Test (int Pregno, int Pscore) //Function 2 { Regno=Pregno;Max=100;Min=40;  Score=Pscore; } ~Test()    //Function 3 { cout<<"Test Over"<<endl; } void Display ( )    //Function 4 { cout<<Regno<<":"<<Max<<":"<<Min<< endl ; cout<<" [Score]"<<Score<<endl ; } } ;

(i) As per object oriented programming which concept is illustrated by function 1 and function 2 together ?
Answer:
Polymorphism
OR
Function Overloading
OR
Constructor Overloading
(1 Mark for naming the concept correctly)
(ii) What is Function 3 specially referred as ? When do you think, Function 3 will be invoked/called ?
Answer:
Destructor is invoked or called when scope of an Object gets over.
(1/2 Mark of naming Destructor correctly)
(1/2 Mark for mentioning correctly when it is invoked)

Question 6:
Answer the questions (i) and (ii) after going through the following class :

class Exam  { int Rno, Maxmarks, MinMarks, marks;  pubic : Exam () //Module 1 { Rno=101;MaxMarks=100;MinMarks=40; Marks =75 ; } Exam (int Prno, int Pmarks) / / Module 2 { Rno = Prno;MaxMarks = l0 0;MinMar ks=40; Marks=Pmarks;  } -Exam ()    //Module 3 { cout<<"Exam Over" <<Endl ; } void show ( )    //module 4 { cout<<Rno<<" : "< <MaxMarks < <":"<< MinMarks <<endl; cout<<"[Marks Got]" <<Marks<<endl; } };

(i) As per Object Oriented Programming, which concept is illustrated by Module 1 and Module 2 together ?
Answer:
Polymorphism
Or
Constructor Overloading
OR
Function Overloading
(1 Mark for mentioning the correct concept)
(ii) What is Module 3 referred as ? When do you think, Module 3 will be invoked/called ?
Answer:
Destructor. It is invoked as soon as the scope of the object gets over.
(1/2 Mark for indentifying it as Destructor)
(1/2 Mark for mentioning correctly when it be called/invoked)

Question 7:
What do you understand by Function overloading or functional polymorphism? Explain with suitable example.
Answer:
Function overloading is a method of using the same function or method to work using different sets of input. It is one of the example of polymorphism, where more than one function carrying similar name behaves differently with different set of parameters passed to them,

void show ()  {  cout<<"
 Hello World!";  }  void show(char na [ ])  {  cout<<"
 Hello Word! Its"<<na;  {

(1 Mark for correct explanation of Function overloading)
(1 Mark for suitable example of Function overloading)