Chapter 1: Overview of CPP | class 12th | Important question Computer Science

Important Questions for Class 12 Computer Science (C++) – C++ Revision Tour

2 Marks Questions

Question 1:
Write the type of C++ tokens (keywords and user defined identifiers) from the following: All Indio 2017

1. new
2. While
3. case
4. Num_2

Аnswer:

1. new → keyword
2. While → user defined identifier
3. case → keyword
4. Num_2 → user defined identifier

Question 2:
Out of the following, find those identifiers, which cannot be used for naming Variable, Constants or Functions in a C++ program: Delhi 2016
Cost, Price*Qty, float, Switch, Address One. Delete, Number12, do
Аnswer:
Price*Qty, float, do and Address One cannot be used for naming variables, constants or functions in a C++ program.

Question 3:
Rewrite the following C++ code after removing any/all syntactical errors with each correction underlined. Delhi 2016
NOTE:  Assume all required header files are already being included in the program.

#define Equation(p,q)=p+2*q 
void main()
{
float A=3.2;B=4.1;
C=Equation(A,B); 
cout<<'Output =’<<C<<endl;
}

Аnswer:

The correct code is:
#define Equation(p,q)(P+2*Q)
void main()
{
float A=3.2,B=4.1; 
float C=Equation(A,B); 
cout<<"0utput ="<<C<<endl;
}

Question 4:
Out of the following, find those identifiers, which cannot be used for naming Variables, Constants or Functions in a C++ program: All India 2016
Fatal*Tax, double, Case, My Name, NeW, switch, Column31,_Amount
Аnswer:
Fatal*Tax, double, My Name, switch cannot be used for naming variables, constants or functions in a C++program.

Question 5:
Rewrite the following C++ code after removing any/all syntactical errors with each correction underlined. All India 2016
NOTE Assume all required header files are already
being included in the program.

#define Formula(a,b)=2*a+b 
void main()
{
float X=3.2;Y=4.1;
Z=Formula(X,Y);
cout<<'Result='<<Z<<endl;
}

Аnswer:

The correct code is:
#define Formula(a.b)(2*a+b)
void main()
{
float X=3.2.Y=4.1: 
float Z=Forinula(X.Y): 
cout<<"Result="<<Z<<endl:
}

Question 6:
Rewrite the following C++ code after removing any/all syntactical errors with each correction underlined. All Indio 2016C NOTE Assume all required header files are already
being included in the program.

define formula(a,b,c)a+2*b+3*c; 
void main()
{
int L=1,M=2,N=3,
J=Formula(L,M,N); 
cout<<'output ='<<J<<endl;
}

Аnswer:

The correct code is:
#define Formula(a,b,c)a+2*b+3*c 
void main()
{
int L=1,M=2,N=3:
int J=formula(L,M,N);
cout<<"0utput="<<j<<endl;
}

Question 7:
Find the correct identifiers Out of the following, which can be used for naming Variable, Constants or Functions in a C ++ program: Delhi 2015
While, for, Float, new, 2ndName, A%B, Amountl2, _Counter
Аnswer:
The correct identifiers are as follows:
While, Float, Amount 12 and_Counter

Question 8:
Find the correct identifiers out of the following, which can be used for naming Variables, Constants or Functions in a C++
For, while, INT, NeW, delete, 1stName, Add+Subtract, name1
Аnswer:
The correct identifiers are as follows:
For, INT, NeW and name1

Question 9:
Observe the following C++ code carefully and rewrite the same after removing all the syntax error(s) present in the code. Ensure that you underline each correction in the code. All India 2013
Important Note:
(i) All the desired header files are already included, which are required to run the code.
(ii) Correction should not change the logic of the program.

//define Change(A,B)2*A+B; 
void maint()
{
Float X,Y,F; 
cin>>X>>Y ;
F=Change[X,Y]; 
cout<<"Result:"<<F<endline;
}

Аnswer:

The correct code is:
#define Change (A.B)(2*A+B) 
void main() 
{
float X.Y.F: 
cin>>X>>Y;
F=Chanae(X.Y):
cout<<"Result:”<<F<<end1:
}

Question 10:
Observe the following OH- code carefully and rewrite the same after removing all the syntax error(s) present in the code. Ensure that you underline each correction in the code.
Important Note:
(i) All the desired header files are already included, which are required to run the code.
(ii) Correction should not change the logic of the program. Delhi 2013

//define Convert(P,Q)P+2*Q; 
void main()
{
Float A,B,Result: 
cin>>A>>B;
Result=Convert[A,B]; 
cout<<"Output:"<<Result<endl:
}

Аnswer:

The correct code is:
#define Convert(P,Q)(P+2*Q) 
void main()
{
float A,B,Result; 
cin >>A>>B;
Result=Convert(A.B): 
cout<<"0utput"<<Result<<endl:
)

Question 11:
Give the difference between the type casting and automatic type conversion. Also, give a suitable C++ code to illustrate both. All India 2012,2011 Delhi 2010
Аnswer:
Type casting It is used by the programmer to convert the value of one type to another type,
e.g. float X=(float) 15/6:
Automatic type conversion It is automatically done by the compiler itself wherever required.
e.g. float X=3;

Question 12:
What is the difference between local variable and global variable? Also, give a suitable C++ code to illustrate both. Delhi 2011
Аnswer:
A variable which is declared within the body of a function and accessible only within the function is known as local variable.
A variable which is declared outside any function and accessible to all functions in a program is known as global variable.
To illustrate this, below is given programming example:

#include<iostream.h>
float area;     //Global variable
void cirarea()
{
float r;   //Local variable
cin>>r
area=3.14*r*r; 
cout<<area; 
}
void rectarea()
{
float l,b; //Local variables
cin>>l>>b;
area=l*b;
cout<<area;
}
void main()
{
cirarea(); 
rectarea();
}

Question 13:
What is the function of typedef in C++? Also, give a suitable C++ code to illustrate it. Delhi 2011C
Аnswer:
typedef keyword is used to assign alternative names to existing types.
e.g. typedef int in;
Now, whenever we want to declare a variable of type integer, rather than using int we can use ‘in’
keyword in place of int.
e.g.

void main()
{
typedef int in;
//in is an alternative name to int in a=10;
//a is of type integer cout<<a;
}

Question 14:
What is the function of #define keyword? Give an example to illustrate its use. Delhi 2009C
Аnswer:
#define keyword is a preprocessor directive that is used to define a macro or a symbolic constant.
Syntax
#define macroname expression
or
#define symbolic constant-value
e.g.
#define Area(R) 3.14*R*R
#define Max 100

Topic – 2
Control Flow and Functions Control Flow

1 Mark Questions

Question 1:
Ronica Jose has started learning C++ and has typed the following program. When she compiled the following code written by her, she discovered that she needs to include some header files to successfully compile and execute it. Write the names of those header files, which are required to be included in the code.

void main() 
double X,Times,Result; 
cin>>X>>Times;
Result=pow(X,Times); 
cout<<Result<<endl ;

All India 2016
Аnswer:
Ciostream. h>→cout, cin
<math. h>→pow()

Question 2:
Jayapriya has started learning C++ and has typed the following program. When she compiled the following code written by her, she discovered that she needs to include some header files to successfully compile and execute it. Write the names of those header files, which are required to be included in this code.

void main()
{
float A,Number,Outcome; 
cin>>A>>Number;
Outcome=pow(A,Number); 
cout<<Outcome<<endl;
} Delhi 2016

Аnswer:
<iostream.h>→cout, cin
<math.h>→pow( )

Question 3:
Ahmad has started learning C++ and has typed the following program. When he compiled the following code written by him, he discovered that he needs to include some header files to successfully compile and execute it. Write the names of those header files, which are required to be included in the code.

void main() 
float Radians,Value; 
cin>>Radians;
Value=sin(Radians); 
cout<<value<<endl;
} All India 2016C

Аnswer:
<iostream.h>→cout, cin
<math.h>→sin( )

Question 4:
Observe the following C ++ code and write the name(s) of the header file(s), which will be essentially required to run it in a C ++ compiler.

void main()
{
float Area,Side;
cin>>Area;
Side=sqrt(Area);
cout<<"0ne Side of the Square:"<<Side<<endl;
} All India 2013

Аnswer:
<iostream.h>→ cout,cin
<math.h> →sqrt( )

Question 5 :
Observe the following C ++ code and write the name(s) of the header file(s), which will be essentially required to run it in a C++ compiler.

void main()
{
int Number;
cin>>Number;
if(abs(Number) == Number); 
cout<<"Positive"<<endl;
} Delhi 2013

Аnswer:
<iostream.h>→ cout, cin
<math.h>→abs( )

Question 6:
Name the header file(s), which are essentially required to run the following program segment.

void main()
}
char A='K',B;
if(islower(A))
B=toupper(A);
else
B='*';
cout<<A<<"turned to"<<B<<endl:
} Delhi 2013C

Аnswer:
<iostream.h>→cout,cin
<ctype.h>→ islower( ); i supper( )

Question 7:
Write the names of the header files to which the following belong:

1. puts( )
2. sin( ) Delhi2009

Аnswer:
puts( )→<stdio.h>
sin( )→<math.h>

Question 8:
Write the names of the header files to which the following belong:

1. setw( )
2. sart( ) All India 2009

Аnswer:
setw( )→<iomanip.h>
sqrt( )→<math.h>

Question 9:
Write the names of the header files to which the following belong:

1. puts( )
2. randomizer( ) Delhi2009c

Аnswer:
puts( )→<stdio.h>
randomize( )→<stdlib.h>

2 Marks Questions

Question 10:
Rewrite the following C++ code after removing any/all syntactical errors with each correction underlined.
NOTE: Assume all required header files are already being included in the program.

void main()
{
cout<<"Enter an Alphabet:"; 
cin>>CH ;
switch(CH) 
case 'A' cout<<"Ant";Break; 
case ’B' cout<<"Bear”;Break;
} All India 2017

Аnswer:

The correct code is:
void main()
{
char CH:
cout<<”Enter an Alphabet:";
cin>>CH ;
switch(CH)
{
case 'A': cout«"Ant"; break:
case 'B'x cout<<"Bear"; break:
}
}

Question 11:
Observe the following C++ code very carefully and rewrite it after removing any/all syntactical errors with each correction underlined.
NOTE Assume all required header files are already being included in the program.

#Define float MaxSpeed = 60.5; 
void main()
int MySpeed 
char A!ert =‘N’; 
cin>>MySpeed; 
if MySpeed>MaxSpeed 
Alert ='Y’; 
cout<<Alert<<endline;
} All India 2015

Аnswer:

The correct code is:
#define float Max Speed = 60.5; 
void main() 
{
int MySpeedi;
char Alert = 'N'; 
cin>>My Speed; 
if(MySpeed>MaxSpeed) 
Alert = 'y';
cout<<Alert<<endl;
}

Question 12:
Write the output of the following C ++ program code:
NOTE Assume all required header files are already being included in the program.

void Location(int &X, int Y=4) 
Y += 2;
X += Y;
}
void main()
{
int PX=10, PY=2;
Location(PY); 
cout<<PX<<","<<PY<<endl; 
location(PX,PY); 
cout<<PX<<","<<PY<<endl;
} All Indio 2015

Аnswer:
The output will be
10, 8
20, 8

Question 13:
Observe the following C++ code very carefully and rewrite it after removing any/all syntactical errors with each correction underlined.
NOTE Assume all required header files are already being included in the program.

//Define float Max=70.0;
Void main()
{
int Speed 
char Stop='N'; 
cin>>Speed; 
if Speed>Max
Stop='Y;
cout<<Stop<<end;
} Delhi 2015

Аnswer:

The correct code is:
#define float Max = 70.0;
void main()
{
int Speed; 
char stop = 'N'; 
cin>>Speed; 
if(Speed>Max)
Stop = 'Y'; 
cout<<Stop<<endl;
}

Question 14:
Write the output of the following C++ program code:
NOTE Assume all required header files are already being included in the program.

void Position(int &Cl,int C2=3)
{ 
Cl+=2;
C2+=Y;
}
void main()
{
int P1=20, P2=4; 
Position(P1); 
cout<<Pl<<","<<P2<<endl; 
Position(P2,P1); 
cout<<Pl<<","<<P2<<endl;
} Delhi 2015

Аnswer:
This program code will give error, i.e Y is undefined symbol.

Question 15:
Write the output of the following C ++ program code:
NOTE Assume all required header files are already being included in the program.

void Draw(int & N, CharMark='#')
{
for(int 1=1;I<=N;I++)
cout<<Mark<<endl;
N++;
}
void main()
{
int Count=3; char Sign='*';
Draw(count);
Draw(Count,Sign);
Draw(Count,'&');
} All India 2015C

Аnswer:
The output will be:
#
#
#
*
*
*
*
&
&
&
&
&

Question 16:
Write a user defined function DIVT( ) which takes an integer as parameter and returns whether it is divisible by 13 or not. The function should return 1 if it is divisible by 13, otherwise it should return 0. All India 2014C
Аnswer:

int DIVT(intx)
{ 
if(%u == 0)
return 1; 
else
return 0;
}

Question 17:
What is the difference between actual and formal parameter? Give a suitable example to illustrate using a C++ code.
Delhi 2014
or
Difference between the actual parameters and formal parameters. Also, give a suitable C++ code to illustrate both.
Delhi 2013C; Delhi 2012; All India 2009
Аnswer:
Differences between actual and formal parameters are as follows:

Actual Parameter	Formal Parameter
Parameters provided at the time of function calling are called actual parameters. These parameters contain actual values.	Parameters provided at the time of function definition are called formal parameters.These parameters are simple variable declarations, i.e. they do not contain actual values.

e.g. #inc1ude<iostream.h> 
#include<conio.h> 
void swap(int n1, int n2)   //Formal Parameters
{
int temp = n1; 
n1=n2; 
n2=temp;
cout<<"Values of numl and num2 after swapping:"; 
cout<<n1<<" "<n2;
}
void main()
{
int num1, num2; 
cout<<"Enter two numbers:"; 
cin>>num1>>num2; 
swap(num1,num2);   //Actual Parameters
getch();
}

Question 18:
Find the output of the following program: All India 2014C

#include<iostream.h>
void in(int x, int y, int &z)
}
x+=y;
y--;
z*=(x-y);
}
void out(int z, int y, int &x)
{
x*=y; 
y ++;
z/=(x+y); 
}
void main()
{
int a=20, b=30, c=10; 
out(a,c,b);
cout<<a<<"#"<<b<<"#"<<c<=><"#"<<endl: 
in(b,c,a):
cout<<a<<"@"<<b<<''@"<<c=><<"#"<<endl; 
out(a,b,c);
cout<<a<<"$"<<b<<"$"<<c<<”=>$"<<endl;
}

Аnswer:
Output
20#300#10#
602 0@ 3 0 0@10@
6020$300$3000$

Question 19:
What is the benefit of using default parameter/argument in a function? Give a suitable example to illustrate it using C++ code. All Indio 2013
Аnswer:
A default parameter is a function parameter that has a default value provided to it. If the user does not supply a value for this parameter, the default value will be used. If the user supply a value for the default parameter, the user-supplied value is used. Consider the following program:

void PrintValues(int nValue1, int nValue2=10) 
{
cout<<"1st value:"<<nValue1<<endl; 
cout<<"2nd value :"<<nValue2<<endl;
}
void main()
{
PrintValues(1);   //nValue2 will use default parameter of 10
PrintValues(3.4);  //override default value for nValue2
}
This program produce the following output :
1st value: 1 
2nd value: 10 
1st value: 3 
2nd value: 4

Question 20:
What is the benefit of using function prototype for a function? Give a suitable example to illustrate it using a C++ code
Delhi 2013
Аnswer:
The function prototype serve to ensure that calls to the function are made with the proper number and types of arguments. In the case of function overloading, the different prototypes serve to distinguish which version of the function to call. The computer will complain with an error, if no function prototype is found for any particular call to function.

e.g.
#include<iostream.h>
int square(int);    //Function prototype
void main()
for(int x=l;x<=10;x++) 
cout<<square(x)<<" ":
cout<<endl;
}
int square(int y)   //Function definition
{
return y*y;
}

Question 21:
Find out the expected correct output(s) from the options (i) to (iv) for the following C++ code. Also, find out the minimum and the maximum value that can be assigned to the variable stop used in the code.

void main()
{
randomize();
int Begin=3,stop;
for(int Run=l;Run<4;Run++)
{
stop=random(Begin)+6; 
cout<<Begin++<<stop<<”*";
}
}
(i) 36*46*59*
(ii) 37*46*56*
(iii) 37*48*57* 
(iv) 35*45*57* Delhi 2013C

Аnswer:
Expected output : (ii), (iii)
Minimum value is 6
Maximum value is 8

Question 22:
Go through the C++ code shown below and find out the possible output or output from the suggested output (i) to (iv). Also, write the least value and highest value, which can be assigned to the variable Guess.

#include<iostream.h> 
#include<stdlib.h> 
void main()
{
randomze(); 
int Guess, High=4; 
Guess=random(High)+50; 
for(int C=Guess;C<=55;C++) 
cout<<C<<"#";
(i) 50#51#52#53#54#55#
(ii) 52#53#54#55#
(iii) 53#54#
(iv) 51#52#53#54#55 Delhi 2011

Аnswer:
Possible outputs are (i), (ii)
Least value of Guess = 50
Highest value of Guess = 53

Question 23:
Go through the C++ code shown below, and find out the possible output or output from the suggested Output Options (i) to
(iv) . Also, write the minimum and maximum values, which can be assigned to the variable MyNum.

#include<iostream.h>
#include<stdlib.h> 
void main()
{
randomize(); 
int MyNum,Max=5; 
MyNum=20+random(Max); 
for(int N=MyNum;N<=25;N++) 
cout<<N<<"*";
}
(i) 20*21*22*23*24*25 
(ii) 22*23*24*25*
(iii) 23*24*
(iv) 21*22*23*24*25 All India 2011

Аnswer:
The possible outputs is (ii)
The minimum value of MyNum = 20
The maximum value of MyNum = 24

Question 24:
The following code is from game, which generates a set of 4 random numbers. Yallav is playing this game, help him to identify the correct option(s) out of the four choices given below as the possible set of such numbers generated from the program code, so that he wins the game. Justify your answer.

#include<iostream.h> 
#include<stdlib.h> 
const int Low=15; 
void main()
{
randomize();
int P0INT=5,Number;
for(int 1=1;I<=4;I++)
{
Number=Low+random(POINT); 
cout<<Number<<":";
(i) 19 : 16 : 15 : 18 :
(ii) 14 : 18 : 15 : 16 :
(iii) 19 : 16 : 14 : 18 :
(iv) 19 : 16 : 15 : 16 : Delhi 2010

Аnswers:
(iv) 19 : 16 : 15 : 16 :

Question 25:
The following code is from a game, which generates a set of 4 random numbers. Praful is playing this game, help him to identify the correct option(s) out of the four choices given below as the possible set of such numbers generated from the program code, so that he wins the game. Justify your answer.

#include<iostream.h> 
#include<stdlib.h> 
const int Low=25; 
void main()
{
randomize();
int P0INT=5,Number;
for(int I=1;I<=4;I++)
{
Number=Low + random(POINT); 
cout«Number<<":”; 
POINT--;
}
}

Аnswer:
(iv) 29 : 26 : 25 : 26 :

Question 26:
Study the following program and select the possible output from it

#include<iostream.h> 
#include<stdlib.h> 
const int LIMIT=4; 
void main()
{
randomize(); 
int Points;
Points=100+random(LIMIT); 
for(int P=Points';P>=100;P--) 
cout<<P<<"#"; 
cout<<endl;
}
(i) 103 # 102 # 101 # 100 #
(ii) 100 # 101 # 102 # 103 #
(iii) 100 # 101 # 102 # 103 # 104 #
(iv) 104 # 103 # 102 # 101 # 100 # Delhi 2009

Аnswers:
(i) 103 # 102 # 101 # 100#

Question 27:
Study the following program and select the possible output from it

#include<iostream.h> 
#include<stdlib.h> 
const int MAX=3; 
void main()
{
randomize(); 
int Number;
Number=50+random(MAX); 
for(int P=Number;P>=50;P--) 
cout<<P<<"#”; 
cout<<endl;
}
(i) 53 # 52 # 51 # 50
(ii) 50 # 51 # 52 #
(iii) 50 # 51 #
(iv) 51 # 50 # All India 2009

Аnswers:
(iv) 51 # 50 #

Question 28:
In the following program, find the correct possible output(s) from the options

#include<iostream.h>
#include<stdlib.h> 
void main()
{
randomize(); 
int x=125,y=99; 
int a=random(3)+4; 
int b=random(2)+2; 
for(int i=0;i<a;i++) 
cout<<"&”; 
cout<<x<<",";
for(i=0;i<b;i++) 
cout<<"*"; 
cout<<y<<endl;
}
(i) &&125,*99 
(ii) &&125,**99
(iii) &&&&&&125,**99 
(iv) &&&&125,***99

Аnswers:
(iii) &&&&&&125, **99
(iv) &&&&125, ***99