The document provides examples to illustrate the differences between various C++ concepts: 1) It compares call by value and call by reference, showing that call by reference updates the original variable unlike call by value. 2) It contrasts automatic type conversion and type casting, demonstrating that automatic conversion happens implicitly while type casting is explicit. 3) It distinguishes between local and global variables by defining local variables' scope as within a function, while global variables can be accessed anywhere.

1. XII CBSE
Previous Year
Question Paper
QUESTION NO
1 (a)
1 OR 2 Marks

2. 1
1. (a) Name the header file to
which the following belong
1
(i) abs( )
(ii) isupper( ) 2006
Delhi
1. (a) (i) math.h (ii) ctype.h

3. 2
1. (a) Name the header file to which
the following belong :
1
(i) pow()
(ii) random() 2006
OD
1. (a) (i) math.h / complex.h (ii)

4. 3
1. (a) Differentiate between a Logical
Error and Syntax Error. Also give
suitable examples of each in C++. 2
2007 Delhi
1. (a) Logical Error:
Error occurred due to incorrect logic applied by the
programmer.
Syntax Error:
Error occurred due to not following the proper
grammar/syntax of the language
OR
Error occurred due to violating rules of the
programming language

5. Example:
//Program to find area and perimeter of rectangle
void main()
{
int A,B,AR,P;
A=10;
B=20;
AR=2*(A*B); //Logical Error – Wrong Formula
P=2*(A+B);
cout<<A<<P>>endl; //Syntax Error – Use of >> with cout
}
(½ Mark for each correct explanation of Logical Error and Syntax
Error)
(½ Mark for each correct example of Logical Error and Syntax
Error)
OR
(Full 2 Marks for correct examples demonstrating the difference
between Logical Error and Syntax Error)
Note: Only 1 Mark to be awarded if Explanation is given without
supporting example.

6. 4
1. (a) Differentiate between a Run Time
Error and Syntax Error. Also give suitable
examples of each in C++. 2
2007 OD
1. (a) Run Time Error : Error occurring in a program during its
execution. Program execution halts when such an error is
encountered.
Example:
int A,B,C;
cin>>A>>B;
C=A/B;//Runtime error if value of B is zero.
Syntax Error: Error occurred due to wrong syntax of language
detected by the compiler during compilation.
Example:
cout>>”A C++ Program”;
(½ Mark for each correct explanation of Runtime Error and Syntax
Error)

7. (½ Mark for each correct example of Runtime Error
and Syntax Error)
OR
(Full 2 Marks for correct examples demonstrating the
difference
between Runtime Error and Syntax Error)
OR
(Only 1 Mark to be awarded if Explanation with out
supporting
examples)

8. 5
1. (a) What is the difference between #define
and const? Explain with suitable example. 2
2008 D
#define: It is a pre-processor directive in C++ for creating a Macro.
Example:
#define sqr(i) i*i
const: It is an Access Modifier in C++ that assigns a constant (non
modifiable) value to a variable. Any attempt in modifying the value
assigned to such a variable is reported as an error by the compiler.
Example:
const float Pi = 3.14;
(½ Mark for each correct explanation of #define and const)
(½ Mark for each correct example of #define and const)
OR
(Full 2 Marks for correct examples demonstrating the difference
between #define and const)
OR
(Only 1 Mark to be awarded if Explanation without supporting
examples)

9. 6
(a) What is the purpose of using a typedef command in C++.
Explain with suitable example. 2
2008 OD
Ans: Typedef:
This keyword allows creating synonyms or aliases for
previously defined data types The general form of typedef is
typedef old_name new_name;
OR
typedef is used for renaming a data type.
Example:
typedef char STR [80]; OR typedef signed char SMALLNUM;
OR typedef float REAL; OR typedef long int BIGNUM;
OR typedef int MAT[2][3] ;
(1 Mark for definition of typedef)
(1 Mark for example of typedef)
OR
(Full 2 Marks for an example with an appropriate explanation)

10. 7
1. (a) What is the difference between call by
value and call by reference? Give an
example in C++ to illustrate both. 2
2009 D
Call by value is used to create a temporary copy of
the data coming from the actual parameter into the
formal parameter. The changes done in the function
in formal parameter are not reflected back in the
calling environment. It does not use ‘&’ sign.
Call by reference is used to share the same memory
location for actual and formal parameters and so
changes done in the function are reflected back in
the calling environment. It uses ‘&’ sign.

11. void Compute(int A, int &B)
{
A++;
B++;
cout<<”In the function”<<endl;
cout<<”A=”<<A<<“&”<<“B=”<<B<<endl;
}
void main ()
{
int I=50,J=25;
cout<<”Before function call “<<endl;
cout<<”I=”<<I<<”&”<<”J=”<<J <<endl;
Compute (I,J) ;
cout<<”After function call “<<endl;
cout<<I=”<<I<<”&”<<”J=”<<J <<endl;
}

12. OUTPUT
Before function call
I=50&J=25
In the function
A=51&B=26
After function call
I=50&J=26
(½ Mark for each correct explanation of Call by Value and Call by
Reference)
(½ Mark for each correct example of Call by Value and Call by
Reference)
OR
(Full 2 Marks for correct examples demonstrating the difference
between
Call by Value and Call by Reference)
OR
(Only 1 Mark to be awarded if Explanation without supporting
examples)
Note: Output is optional

13. 8
1. (a) What is the difference between
Actual Parameter and Formal Parameter?
Give an example in C++ to illustrate both
types of parameters.
2
2009 ODA parameter used in the function call is known as Actual
Parameter. It is used to send the data to function. A
parameter used in the function definition is known as
Formal Parameter, It is used to accept the data from actual
parameter.
void Seventimes(int A)//A is formal parameter
{
cout<<7*A;
}

14. void main ()
{
int P=6;
Seventimes(P);//p is actual parameter
}
(½ Mark for each correct explanation of Actual
Parameter and Formal Parameter)
(½ Mark for each correct example of Actual Parameter
and Formal Parameter)
OR
(Full 2 Marks for correct examples demonstrating the
difference between Actual Parameter and Formal
Parameter)
OR
(Only 1 Mark to be awarded for Explanation given
without supporting examples)

15. 9
1. (a) What is the difference between automatic
type conversion and type casting? Also, give a
suitable C++ code to illustrate both. 2
2010 D
Automatic Type Conversion: it is an implicit process of conversion
of a data from one type to another. For example
int N = 65;
char C = N; // Automatic type conversion
cout<<C;
OUTPUT:
A
Type Casting: It is an explicit process of conversion of a data from
one type to another. For example

16. int A=1, B=2;
float C = (float)A/B; //Type Casting
cout<<C;
OUTPUT:
0.5
(½ Mark for each correct explanation of Automatic Type
Conversion and Type Casting)
(½ Mark for each correct example of Automatic Type
Conversion and Type Casting)
OR
(Full 2 Marks for correct example(s) demonstrating the
meaning of / difference between Automatic Type
Conversion and Type Casting)
OR
(Only 1 Mack to be awarded if Explanation without
supporting examples)
Note: Output is optional

17. 10
1. (a) What is the difference between call by
value and call by reference? Give an
example in C++ to illustrate both. 2
2010 OD
Call by value is used to create a temporary copy of
the data coming from the actual parameter into the
formal parameter. The changes done in the
function in formal parameter are not reflected back
in the calling environment. It does not use ‘&’ sign.
Call by reference is used to share the same
memory location for actual and formal parameters
and so changes done in the function are reflected
back in the calling environment. It uses ‘&’ sign.

18. void Compute(int A, int &B)
{
A++;
B++;
cout<<”In the function”<<endl;
cout<<”A=”<<A<<“&”<<“B=”<<B<<endl;
}
void main ()
{
int I=50,J=25;
cout<<”Before function call “<<endl;
cout<<”I=”<<I<<”&”<<”J=”<<J <<endl;
Compute (I,J) ;
cout<<”After function call “<<endl;
cout<<I=”<<I<<”&”<<”J=”<<J <<endl;
}

19. OUTPUT
Before function call
I=50&J=25
In the function
A=51&B=26
After function call
I=50&J=26
(½ Mark for each correct explanation of Call by Value and Call by
Reference)
(½ Mark for each correct example of Call by Value and Call by
Reference)
OR
(Full 2 Marks for correct examples demonstrating the difference
between
Call by Value and Call by Reference)
OR
(Only 1 Mark to be awarded if Explanation without supporting
examples)
Note: Output is optional

20. 11
1. (a) What is the difference between Local
Variable and Global Variable? Also, give a suitable
C++ code to illustrate both. 2
2011 D
Local Variables: Local variables are those variables
which are declared within a function or a compound
statement and these variables can only be used within
that function/scope.
Global Variables: Global variables are those variables
which are not declared within any function or scope. So,
these variables can be accessed by any function of the
program

21. Example
#include<iostream.h>
#include<conio.h.>
int G; // Global variable declared
void Fun ( )
{
int L = 25; // Local variable of function Fun ( ) assigned value 25
G=5; // Global Variable is accessed and assigned value 5
Cout<<G<<endl; // Value of global variable is displayed as 5
Cout<<L<<endl; // Value of local variable is displayed as 25
}
void main ( )
{
Fun ( ) ; // Function call
G = G + 5; // Global variable is incremented by 5
cout<<G<<endl; // Global variable is displayed as 10
}
(½ Mark for each correct explanation of Local Variable and Global
Variable)
(½ Mark for each correct example of Local variable and Global Variable)
OR
(Full 2 Maries for correct example(s) demonstrating the meaning of /
difference between Local Variable and Global Variable) OR
(Only 1 Mark to be awarded if Explanation without supporting examples)

22. 12
1. (a) What is the difference between automatic
type conversion and type casting? Also, give a
suitable C++ code to illustrate both. 2
2011 OD
Automatic Type Conversion: it is an implicit process of conversion
of a data from one type to another. For example
int N = 65;
char C = N; // Automatic type conversion
cout<<C;
OUTPUT:
A
Type Casting: It is an explicit process of conversion of a data from
one type to another. For example

23. int A=1, B=2;
float C = (float)A/B; //Type Casting
cout<<C;
OUTPUT:
0.5
(½ Mark for each correct explanation of Automatic Type
Conversion and Type Casting)
(½ Mark for each correct example of Automatic Type
Conversion and Type Casting)
OR
(Full 2 Marks for correct example(s) demonstrating the
meaning of / difference between Automatic Type
Conversion and Type Casting)
OR
(Only 1 Mack to be awarded if Explanation without
supporting examples)
Note: Output is optional

24. 13
1. (a) What is the difference between Global Variable and Local Variable?
Sample Paper Set I 2009
Global Variable Local Variable
It is a variable, which is declared outside all
the functions
It is accessible throughout the program
It is a variable, which is declared with
in a function or with in a compound
statement
It is accessible only within a
function/compound statement in which
it is declared.
Example :
#include <iostream.h>
float NUM=900; //NUM is a global variable
void LOCAL(int T)
{
int Total=0; //Total is a local variable
for (int I=0;I<T;I++)
Total+=I;
cout<<NUM+Total;
}
void main()
{
LOCAL(45);
}

25. 14
1.
(a) What is the difference between Object Oriented
Programming and Procedural Programming? 2
Sample Paper Set II 2009
Object Oriented
Programming
Procedural
Programming
Emphasis on Data
Follows Bottom-Up approach in
program design
Data hiding feature prevents
accidental change in data
Features like data
encapsulation, polymorphism,
inheritance are present
Emphasis on doing things
(functions)
Follows Top-down
approach in program design
Presence of Global
variables increase chances
of accidental change in data
Such features are not
available

26. 15
1. (a) What is the difference between Global Variable and Local Variable?
(Sample Paper 2010 (Repeated it was asked in Sample Paper Set 1 2009) )
Global Variable Local Variable
It is a variable, which is declared outside all
the functions
It is accessible throughout the program
It is a variable, which is declared with
in a function or with in a compound
statement
It is accessible only within a
function/compound statement in which
it is declared.
Example :
#include <iostream.h>
float NUM=900; //NUM is a global variable
void LOCAL(int T)
{
int Total=0; //Total is a local variable
for (int I=0;I<T;I++)
Total+=I;
cout<<NUM+Total;
}
void main()
{
LOCAL(45);
}

27. 16
Sample Paper Set II - 2010 (asked in 2009 OD)
Actual Parameter Formal Parameter
It is a parameter, which is used in function
call to send the value from the calling
environment.
It is the parameter, which is
used in function header, to
receive the value from the
actual parameter.
Example :
#include <iostream.h>
void Calc ( int T ) // T is formal parameter
{
cout<< 5 * T;
}
void main ( )
{
int A=45;
Calc ( A ); // A is actual parameter
}
(1 Mark for stating difference)
( 1 Mark for the suitable example)
OR
(Full 2 Marks for explanation of differences with the help of example)
( 1 Mark for the example)
1 ( a ) What is the difference between Actual Parameter and Formal
Parameters ? Also, give a suitable C++ code to illustrate both. 2

28. 17
Sample Paper Set I - 2012
Post-increment Pre-increment
++ is an increment operator to increment
the value of a variable by one , when used
after the operand it is known as post –
increment operator.
When it is used before an operand to
increment its value by one, it is called
pre – increment operator.
Example :
#include <iostream.h>
void main ( )
{
int NUM=9;
cout<<++NUM ; // 10 will be displayed
cout<<NUM++ ; // 10 will be displayed
Cout<< NUM ; // 11 will be displayed
}
(1 Mark for stating difference)
( 1 Mark for the suitable example)
OR
(Full 2 Marks for explanation of differences with the help of example)
( 1 Mark for the example)
1 (a) Differentiate between the post-increment and pre-increment
operators. Also, give suitable C++ code to illustrate both.

29. 18
Sample Paper Set II - 2010 (asked in 2009 OD and Sample Paper 2010 Set II)
Actual Parameter Formal Parameter
It is a parameter, which is used in function
call to send the value from the calling
environment.
It is the parameter, which is
used in function header, to
receive the value from the
actual parameter.
Example :
#include <iostream.h>
void Calc ( int T ) // T is formal parameter
{
cout<< 5 * T;
}
void main ( )
{
int A=45;
Calc ( A ); // A is actual parameter
}
(1 Mark for stating difference)
( 1 Mark for the suitable example)
OR
(Full 2 Marks for explanation of differences with the help of example)
( 1 Mark for the example)
1 ( a ) What is the difference between Actual Parameter and Formal
Parameters ? Also, give a suitable C++ code to illustrate both. 2

30. 19
1. (a) What is the difference between automatic
type conversion and type casting? Also, give a
suitable C++ code to illustrate both. 2
2012 OD ( Repeated, asked in the year 2010 Delhi Paper)
Automatic Type Conversion: it is an implicit process of conversion
of a data from one type to another. For example
int N = 65;
char C = N; // Automatic type conversion
cout<<C;
OUTPUT:
A
Type Casting: It is an explicit process of conversion of a data from
one type to another. For example

31. int A=1, B=2;
float C = (float)A/B; //Type Casting
cout<<C;
OUTPUT:
0.5
(½ Mark for each correct explanation of Automatic Type
Conversion and Type Casting)
(½ Mark for each correct example of Automatic Type
Conversion and Type Casting)
OR
(Full 2 Marks for correct example(s) demonstrating the
meaning of / difference between Automatic Type
Conversion and Type Casting)
OR
(Only 1 Mack to be awarded if Explanation without
supporting examples)
Note: Output is optional

32. THAN
K
YOU