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## Chapter: 11th Computer Science : Chapter 9 : Introduction to C PlusPlus

Short Answers, Explain in Brief, Explain in detail, Important Questions - Science : Introduction to C PlusPlus, Data Types, Variables and Expressions

Introduction to C++

Evaluation

Part – II

1. What is meant by a token? Name the token available in C++.

Answer: The smallest individual unit in a program is known as a Token or a Lexical unit.

C++ has the following tokens:

(i) Keywords

(ii) Identifiers

(iii) Literals

(iv) Operators

(v) Punctuators

2. What are keywords? Can keywords be used as identifiers?

Answer: Keywords are the reserved words which convey specific meaning to the C++ compiler. They are the essential elements to construct C++ programs. No, Keywords cannot be used as an identifier.

3. The following constants are of which type?

(i) 39 (ii) 032 (iii) 0XCAFE (iv) 04.14

(i) Integer constant

(ii) Octal constant

(iv) Floating point constant.

4. Write the following real constants into the exponent form:

(i) 23.197 (ii) 7.214 (iii) 0.00005 (iv) 0.319

(i) 0.23197 × 102 0.23197E02

(ii) 0.7214×101 0.7214E01

(iii) 0.5×10-4 0.5E.04

(iv) 0.0319×101 0.0319E01

5. Assume n=10; what will be result of n>>2;?

n >>2 (00000010)2 210

6. Match the following

A : B

(a) Modulus : (1) Tokens

(b) Separators : (2) Remainder of a division

(c) Stream extraction : (3) Punctuators

(d) Lexical Units : (4) get from

[ Answer: (a) - (2), (b)- (3), (c) - (4), (d) - (1)]

(a) Modulus - (2) Remainder of a division

(b) Separators - (3) Punctuators

(c) Stream extraction - (4) get from

(d) Lexical Units - (1) Tokens

Part – III

1. Describe the differences between keywords and identifiers? Keywords

Keywords are the reserved words which convey specific meaning to the C++. Keywords can not be used as an identifier.

Example: Switch, case, for, if etc.,

Identifiers

Identifiers are the user defined names given to different parts of the C++ program. Identifiers are not reserved.

Example: name, age, class-12B etc.,

2. Is C++ case sensitive? What is meant by the term “case sensitive”?

Answer: Yes, C++ is case sensitive. Case sensitive means C++ treats upper and lower case characters differently. Capital letters ≠ small letters.

3. Differentiate “=” and “==”. =

(i) It is an assignment operator.

(ii) It is used to assign a value to a variable which is on the left hand side of an assignment statement.

(iii) Eg: a = b (b value is assigned to a)

= =

(i) It is a relational operator.

(ii) It is used to compare two values and the result wall be either true or false.

(iii) Eg: a = = b (a value will be compared with b value)

4. Assume a=10, b=15; What will be the value of a^b?

10 Ʌ 15

1010 = 10102

1510 = 11112 aɅb = 01012 = 510

5. What is the difference between “Run time error” and “Syntax error”? Syntax error

(i) Syntax is a set of grammatical rules to construct a program.

(ii) Syntax errors occur when grammatical rules of C++ are violated.

(iii) Example: if a program tries to open a file which does not exist, it results in a run time error.

Run-time error

(i) A run time error is that occurs during the execution of a program.

(ii) It is occurs because of some illegal operation that takes place.

(iii) Example: if a program tries to open a file which does not exist, it results in a run time error.

6. What are the differences between “Logical error” and “Syntax error”? Syntax error

(i) Syntax is a set of grammatical rules to construct a program.

(ii) Every programming language has unique rules for constructing the source code. (iii) Syntax errors occur when grammatical rules of C++ are violated.

Logical error

(i) A Program has not produced expected result even though the program is grammatically correct. It may be happened by wrong use of variable / operator / order of execution etc.

(ii) This means, program is grammatically correct, but it contains some logical error.

(iii) Semantic error is also called as "Logic Error".

7. What is the use of a header file?

Answer: Header files contain definitions of functions and variables, which is used into any C++ program by using the pre-processor #include statement. It have an extension ".h" which contains C++ function declaration and macro definitions.

8. Why is main function special?

Answer: C++ program is a collection of functions. Every C++ program must have a main function. The main( ) function is the starting point where all C++ programs being their execution. Therefore, the executable statements should be inside the main ( ) function.

9. Write two advantages of using include compiler directive.

Answer: The preprocessor directive # include tells the computer to insert another file in to the source file.

(i) The program is broken down into modules thus making it more simplified

(ii) More library functions can be used at the same time size of the program is retained.

10. Write the following in real constants.

(i) 15.223 (ii) 211.05 (iii) 0.00025

(i) 1.5223 × 101 1.5223E−1

(ii) 2.1105 × l02 2.1105E−2

(iii) 25 × l0−5 25E −5

Part – IV

1. Write about Binary operators used in C++.

Answer: Binary Operators - Require two operands

(i) Arithmetic Operators

(ii) Relational Operators.

(iii) Logical Operators

(iv) Bitwise Operators

(v) Assignment Operators

(vi) Conditional Operator

(i) Arithmetic Operators : Arithmetic operators perform simple arithmetic operations like addition, subtraction, multiplication, division etc.,

(ii) Relational Operators : Relational operators are used to determine the relationship between its operands. When the relational operators are applied on two operands, the result will be a Boolean value i.e 1 or 0 to represents True or False respectively. C++ provides six relational operators.

(iii) Logical Operators : A logical operator is used to evaluate logical and relational expressions. The logical operators act upon the operands that are themselves called as logical expressions. C++ provides three logical operators.

(iv) Bitwise Operators : Bitwise operators work on each bit of data and perform bit-by-bit operation. In C++, there are three kinds of bitwise operators, which are:

(1) Logical bitwise operators

(2) Bitwise shift operators

(3) One’s complement operators

(v) Assignment Operators : Assignment operator is used to assign a value to a variable which is on the left hand side of an assignment statement. = (equal to) is commonly used as the assignment operator in all computer programming languages. This operator copies the value at the right side of the operator to the left side variable. It is also a binary operator.

(vi) Conditional Operators : In C++, there is only one conditional operator is used. ?: is a conditional Operator. This is a Ternary Operator. This operator is used as an alternate to if... else control statement.

2. What are the types of Errors?

Syntax Error:

Syntax is a set of grammatical rules to construct a program. Every programming language has unique rules for constructing the source code.

Syntax errors occur when grammatical rules of C++ are violated.

Example: If you type as follows, C++ will throw an error, cout <<”Welcome to Programming in C++” As per grammatical rules of C++, every executable statement should terminate with a semicolon. But, this statement does not end with a semicolon.

Semantic Error:

A Program has not produced expected result even though the program is grammatically correct. It may be happened by wrong use of variable/ operator /order of execution etc. This means, program is grammatically correct, but it contains some logical error. So, Semantic error is also called as ’’Logic Error”.

Run-time error:

A run time error is that occurs during the execution of a program. It is occurs because of some illegal operation that takes place.

For example, if a program tries to open a file which does not exist, it results in a run-time error.

3. Assume a=15, b=20; What will be the result of the following operations?

(a) a&b (b) a|b (c) a^b (d) a>>3 (d) (~b)

(a) a&b = (00000100)2 = (4)10

(b) a|b = (00011111)2 = (31)10

(c) aɅb = (00011011)2 = (27)10

(d) a>>3 = (00000001)2 = (1)10

(e) (~b) = (00001011)2 = (11)10

EVALUATE YOURSELF

1. What is meant by literals? How many types of integer literals available in C++?

(i) Literals are data items whose values do not change during the execution of a program. Therefore Literals are called as Constants.

(ii) Three types of integer 1. Decimal 2. Octal 3. Hexadecimal

2. What kind of constants are following?

(i) 26 (ii) 015 (iii) 0×F (iv) 014.9

(i) Integer

(ii) Octal

(iv) Floating

3. What is character constant in C++?

Answer: A character constant in C++ must contain one character and must be enclosed in a single quote. Valid character constants : 'A', '2', ‘\$’

4. How are non graphic characters represented in C++?

Answer: Non- printable characters can be represented by using escape sequences. An escape sequence is represented by a backslash followed by one or two characters.

5. Write the following real constants into exponent form:

(i) 32.179 (ii) 8.124 (iii) 0.00007

(i) 32179E-3

(ii) 8124E-3

(iii) 7E - 5

6. Write the following real constants into fractional form:

(i) 0.23E4 (ii) 0.517E-3 (iii) 0.5E-5

(i) 0.000023

(ii) 0.000517

(iii) 0.000005

7. What is the significance of null (\0) character in a string?

Answer: Sequence of characters enclosed within double quotes are called as String literals. By default, string literals are automatically added with a special character ‘\0’ (Null) at the end.

Therefore, the string “welcome” will actually be represented as “welcome\0” in memory and the size of this string is not 7 but 8 characters i.e., inclusive of the last character \0.

8. What is the use of operators?

Answer: Operators are used to perform calculations on an operands that yield a new value.

9. What are binary operators? Give examples of arithmetic binary operators.

Answer: Binary operators are the operators that required two operands.

Eg : x = a + b − c.

10. What does the modulus operator % do?

Answer: Modulus operator (%) is used to get the remainder of two integer division.

Eg: 10% 3 = 1

11. What will be the result of 8.5 % 2?

12. Assume that R starts with value 35. What will be the value of S from the following expression? S=(R −)+(++R).

13. What will be the value of j = - - k + 2k. if k is 20 initially ?

14. What will be the value of p = p * ++j where j is 22 and p = 3 initially?

15. Give that i = 8, j = 10, k = 8, What will be result of the following expressions?

(i) i < k (ii) i < j (iii) i > = k (iv) i = = j (v) j ! = k

(i) False

(ii) True

(iii) True

(iv) False

(v) True

16. What will be the order of evaluation for the following expressions?

(i) i + 3 >= j – 9 (ii) a+10 < p −3 + 2q 17. Write an expression involving a logical operator to test, if marks are 75 and grade is ’A’.

Answer: If (marks > = 75)

cant << "grade is 'A' ;

HANDS ON PRACTICE

Type the following C++ programs in Dev C++ IDE and execute. If compiler shows any errors, try to rectify it and execute again and again till you get the expected result.

1. C++ Program to find the total marks of three subjects.

#include <iostream>

using namespace std;

int main()

{

int ml, m2, m3, sum;

cout << “\n Enter Mark 1: ”;

cin >> m1;

cout<< “\n Enter Mark 2: ”;

cin >> m2;

cout<<”\n Enter Mark 3: ”;

cin >> m3;

sum = ml + m2 + m3;

cout<< ”\n The sum = ” << sum;

}

• Make changes in the above code to get the average of all the given marks.

#include <iostream>

using namespace std;

int main()

{

int ml, m2, m3, avg;

cout << "\n Enter the mark In";

cin >> m1>>m2>>m3;

avg = (ml+m2+m3)/3;

cout <<"The average = "<<avg;

2. C++ program to find the area of a circle.

#include <iostream>

using namespace std;

int main()

{

float area;

cout<< "\n The area of circle =” << area;

}

#include <iostream>

using namespace std;

int main()

{

float r, area;

cin >> r;

area = 3.14 * r * r;

cout<< "\n The Area of the circle is " << area;

}

Output:

The Area of the circle is 132.665

3. Point out the errors in the following program:

Using namespace std;

int main()

{

Cout<< “Enter a value ”;

cin << numl >> num2

num+num2=sum;

cout >>“\n The Sum= ” >> sum;

1. #include<iostream.h>(pre-processor statement missing)

2. int numl, num2; (variable declaration statement missing)

3. cin >> numl >> num2; (instead of extraction operator, insertion operator in the statement)

4. sum = numl + num 2; (always the expression come in RHS)

5. cout << "\n The sum = " << sum; (insertion operator is required)

6. } (to End the program using curly braces)

Corrected program :

#include<iostream.h>

int main ()

{

Cout<< "Enter a value";

cin >> numl >>num2'

sum = num 1 + num2;

cout<< "\n The sum = "<< sum;

}

4. Point out the type of error in the following program

#include <iostream>

using namespace std;

int main()

{

int h=l0; w=12;

cout<< ’’Area of rectangle” << h+w;

}

Answer: int h = 10, w = 12;

Cout<< "Area of rectangle"<<h + w;

Data Types, Variables and Expressions

Evaluation

Part – II

Answers to all the questions (2 Marks):

1. Write a short note const keyword with an example.

Answer: Const is the keyword used to declare a constant. It modifies/restricts the accessibilty of a variable

Eg: const int n = 200;

2. What is the use of setw() format manipulator?

Answer: Setw() manipulator sets the width of the field assigned for the output. The field width determines the minimum number of characters to be written in output. Syntax : setw(number of characters)

3. Why is char often treated as integer data type?

Answer: Character data type is often said to be an integer type, since all the characters are represented in memory by their associated ASCII Codes. If a variable is declared as char, C++ allows storing either a character or an integer value.

4. What is a reference variable? What is its use?

Answer: Reference is an alternative name for a variable. A reference provides an alias for a previously defined variable. Declaration of a reference consists of base type and an & (ampersand) symbol; reference variable name is assigned the value of a previously declared variable.

5. Consider the following C++ statement. Are they equivalent?

char ch = 67;

char ch = ‘C’; 6. What is the difference between 56L and 56?

Answer: 56 is an integer number.

56L is a long integer number.

7. Determine which of the following are valid constant? And specify their type.

(i) 0.5 (ii) ‘Name’ (iii) ‘\t’ (iv) 27,822

(i) 0.5 - Valid Floating Constant

(ii) 'Name' - Invalid String Constant (Enclosed within Double quotes)

(iii) '\t' - Valid - Non graphic character data type

(iv) 27,822 - Invalid Decimal Constant (Commas is not allowed).

8. Suppose x and y are two double type variable that you want add as integer and assign to an integer variable. Construct a C++ statement for the doing so.

doubles x;

double y;

int z = (int) x + (int) y; or int z = (int)(x + y);

9. What will be the result of following if num=6 initially.

(a) cout << num;

(b) cout << (num==5);

(a) 6

(b) 0

10. Which of the following two statements are valid? Why? Also write their result.

int a;

(i) a = 3,014; (ii) a=(3,014);

Answer: (i) Above the two statements is Invalid.

(ii) Special Symbols are not allowed in the integer values ( Commas, Open and Close Brackets).

Part – III

Answers to all the questions (3 Marks):

1. What are arithmetic operators in C++? Differentiate unary and binary arithmetic operators. Give example for each of them.

Answer: (i) The operators, which are applied to perform arithmetical calculations in a program are known as arithmetical operators.

(ii) A unary operator requires a single (one) operand. Unary +, Unary −, ++, − − are the examples of many operators.

(iii) A binary operator requires two operands +, −,*,/, % are the examples of binary operators.

2. Evaluate x+= x + ++x; Let x=5;

Answer: x + = x + + + x

x = x + x+++ x;

= 5 + 5 + 6= 16.

3. How relational operators and logical operators related to one another?

Answer: Logical operators uses AND (&&), OR (||) and NOT(!). These operators yield true or false depending upon the out come of different relational expressions. Relational expressions are formed by Relational operators.

4. Evaluate the following C++ expressions where x, y, z are integers and m, n are floating point numbers. The value of x = 5, y = 4 and m=2.5;

(i) n = x + y / x;

(ii) z = m * x + y;

(iii) z = (x++) * m + x;

(i) n=x+y/x;

n=5+(4/5)

n = 5 + 0.8

n = 5.8

(ii) z = m*x + y;

z = (2.5*5) + 4

z=12.5 + 4

z= 16.5

z = 16 (z is an integer)

(iii) z = (x++) * m + x;

z = ((5++) * 2.5) + 5

z = (5*2.5) + 5

z= 12.5 + 5

z= 17.5

z =17 (z is an integer).

EVALUATE YOURSELF

1. What do you mean by fundamental data types?

(i) Fundamental data types are predefined data types available in C++.

(ii) These are five fundamental data types in C++.

2. The data type char is used to represent characters, then why is it often termed as an integer type?

Answer: Since all the characters are represented in memory by their associated ASCII codes.

3. What is the advantage of floating point numbers over integers?

(i) Floating point number can represent values between the integers.

(ii) Floating point number can represent a much greater range of values.

4. The data type double is another floating point type. Why is it treated as a distinct data type?

Answer: In double data type, more fractions can be accommodated in double than in float data type.

5. What is the use of void data type?

Answer: Void data type is used as a return type for functions that do not return any value.

6. What is modifiers? What is the use of modifiers?

Answer: (i) Modifiers can be used to modify (expand or reduce) the memory allocation of any fundamental data type.

(ii) Modifier is a qualifiers used along with data type.

7. What is wrong with the following C++ statement: long float x;

8. What is a variable ? Why a variable called symbolic variable?

Answer: (i) Variables are user-defined names assigned to specific memory locations in which the values are stored.

(ii) These are called as symbolic variables because these are named locations.

9. What do you mean by dynamic initialization of a variable? Give an example.

(i) A variable can be initialized during the execution of a program. It is known as 'Dynamic initialization.'

(ii) For example : int n1, n2,s; s = n1 +n2. This two statements combined into a single statement using dynamic initialization int s = nl+n2;

10. What is wrong with the following statement? const int x;

Answer: No value specified to the variable x correct statement;

const int x = 100;

11. What is meant by type conversion?

Answer: The process of converting one fundamental type into another is called as "Type conversion".

12. How implicit conversion different from explicit conversion?

Answer: (i) Implicit type conversion is automatically done by compiler.

(ii) Explicit type conversion is done by the programmer.

13. What is difference between endl and \n?

Answer: endl - Inserts a new line and flushes the buffer (Flush means - clean) ‘\n’ - Inserts only a new line.

14. What is the use of references?

15. What is the use of setprecision ( ) ?

Answer: It is used to display numbers with fractions in specific number of digits.

Hands on practice:

1. Write C++ programs to interchange the values of two variables.

a. Using with third variable

b. Without using third variable

a. Using with third variable

#include<iostream.h>

using namespace.std;

int main ()

{

int a, b, t;

cout<<"\n Enter First number";

cin>>a;

cout<<"\n Enter Second number";

cin>>b;

t=a;

a-b;

b=t;

cout<<a<<'\t'<<b;

return 0;

}

b. Without using third variable :

#include<iostream.h>

using namespace.std;

int main ()

{

int a, b;

cout<<"\n Enter First number";

cin>>a;

cout<<"\n Enter Second number";

cin>>b;

a = a+b;

b = a−b;

a = a−b;

cout<<a<<'\t'<<b;

return 0;

}

2. Write C++ programs to do the following:

a. To find the perimeter and area of a quadrant.

b. To find the area of triangle.

c. To convert the temperature from Celsius to Fahrenheit.

a. To find the perimeter and area of a quadrant

#include<iostream.h>

using namespace.std;

int main ()

{

float area, peri, r;

cin>>r;

area=0.25* 3.14*r*r;   //Area= 1/4πr2

peri=0.5*3.14*r;        //perimeter = l/2πr

cout <<"Area of a quadrant = "<<area<endl;

cout<<"Perimeter of a quadant = "<< peri <<endl;

return 0;

}

b. To find the area of triangle :

#include<iostream.h>

using namespace.std;

int main ()

{

float area, b, h;

cout<<"\n Enter base";

cin>>b;

cout<<"\n Enter height";

cin>>h;

area = 0.5*b*h       //Area=l/2 bh

cout <<"Area of a triangle = "<<area<endl;

return 0;

}

c. To convert the temperature from Celsius to Fahrenheit

#include<iostream.h>

using namespace.std;

int main ()

{

float tempC, tempF;

cout<<"\n Enter celcius";

cin>>tempC;

tempF =(tempC * 1.8F)+32;

cout<<"Equivalent temperature of <<tempC <<"in Fahrenheit is"<< tempF<<endl;

return 0;

}

3. Write a C++ to find the total and percentage of marks you secured from 10th Standard Public Exam. Display all the marks one-by-one along with total and percentage. Apply formatting functions.

#include<iostream.h>

#include<iomanip.h>

using namespace std;

int main ()

{

char name;

float E,L,M,S,SS,tot, per;

cout<<"\n Name = ";

cin>> name;

cout <<"\ Enter English, Language, Maths, Science, Social Marks";

cin >> E >> L >> M >> S >>SS;

tot = E+L+M+S+SS;

per = tot/500 * 100;

cout<<setw(20)<<"Name:"<<setw( 10)<< name;

cout <<setw (20) <<"English:" <<setw(10)<< E<<endl;

cout <<setw (20) << "Tamil:"<<setw(10)<< T<<endl;

cout <<setw (20)<<"Maths:"<<setw(10)<< M<<endl;

cout<<setw(20)<<"Science:"<<setw(10)<<S<<endl;

cout<<setw(20)<<"SocialScience:"<< setw(10)<< SS<<endl;

cout <<setw (20) <<"Total:"<< setw( 10)<<tot<<endl;

cout<< setw (20)<< "Percentage:" << setw( 10) << per<<endl;

return 0;

}

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11th Computer Science : Chapter 9 : Introduction to C PlusPlus : Answer the following questions | Introduction to C PlusPlus | Computer Science