# Fundamentals of QBASIC: Constants and Variables

## Choose the correct option

#### Question 1

Which of the following is not a valid numeric constant?

1. -325
2. -99.99
3. \$24
4. 0.00025

\$24

Reason — Numeric constants can only consist of numbers (0 - 9) and decimal sign (.). They cannot have a \$ sign.

#### Question 2

Which of the following is a valid string variable?

1. AB\$
2. AB\$\$
3. \$AB\$
4. \$\$AB

AB\$

Reason — String variables must end with a \$ sign.

#### Question 3

Which of the following is a valid string constant?

1. Computer Science
2. 'Computer Science'
3. "Year - 2022"
4. !!Computer!!

"Year - 2022"

Reason — String constants are always enclosed in double quotes ("").

#### Question 4

Which of the following statements is correct for numeric variables?

1. They cannot store numbers.
2. They are used for mathematical operations.
3. They begin with a dollar sign.
4. They can store string constant.

They are used for mathematical operations.

Reason — Numeric variables store numbers so they are used for mathematical operations.

#### Question 5

Which of the following statements is correct in QBASIC?

1. Negative numbers cannot be assigned to a variable.
2. Only positive numbers can be assigned to a variable.
3. Numeric constant can only be assigned to numeric variables.
4. Numeric variables are assigned to numeric constants.

Numeric constant can only be assigned to numeric variables.

Reason — Numeric variables are used to store numeric values or numeric constants.

## Fill in the blanks

#### Question 1

Alphanumeric variables always end with a dollar (\$) sign.

#### Question 2

Numeric constants include only numbers.

#### Question 3

The maximum length of a variable is 12.

#### Question 4

Alphanumeric constants are always enclosed in double quotes.

#### Question 5

Variables always begin with alphabets.

#### Question 6

A comma is not allowed while writing numeric constants.

## State True or False

#### Question 1

A45 is a valid numeric variable.
True

#### Question 2

A+B is not a valid alphanumeric variable.
True

#### Question 3

Special characters are used in variables.
False

#### Question 4

Numeric constants are stored in numeric variables.
True

#### Question 5

0.5495 is a valid numeric constant.
True

#### Question 6

Decimals are not allowed in numeric constants.
False

## Match the following

#### Question 1

Sl.
No.
Column 1Column 2
1Numeric constantsAlphanumeric constants
2Alphanumeric variables representare always enclosed in " "
3Alphanumeric constantsmust begin with an alphabet
4A variableString variables
5Alphanumeric variables are calledcan take part in mathematical operations

Sl.
No.
Column 1Column 2
1Numeric constantscan take part in mathematical operations
2Alphanumeric variables representAlphanumeric constants
3Alphanumeric constantsare always enclosed in " "
4A variablemust begin with an alphabet
5Alphanumeric variables are calledString variables

## Name the following

#### Question 1

Two types of variables

1. Numeric variables
2. Alphanumeric variables

#### Question 2

Two types of constants

1. Numeric constants
2. Alphanumeric constants

## Correct the following statements

#### Question 1

B\$ = WORLD CUP 2007

B\$ = "WORLD CUP 2007"

#### Question 2

"DELHI PUBLIC SCHOOL" = D\$

D\$ = "DELHI PUBLIC SCHOOL"

#### Question 3

\$\$A = "ARYA PUBLISHING COMPANY"

A\$ = "ARYA PUBLISHING COMPANY"

P\$ = (A + B)2

P = (A + B) ^ 2

#### Question 5

4B\$ = "NEW DELHI"

B4\$ = "NEW DELHI"

#### Question 6

A = 4P + 5Q

A = 4 * P + 5 * Q

#### Question 7

AVG = (2A + 3B + 4C)/3

AVG = (2 * A + 3 * B + 4 * C) / 3

#### Question 8

A*B = AB + CD

AB = A * B + C * D

## Write down the appropriate variables for the following

#### Question 1

_________ = "Understanding Information Technology"

UIT\$ = "Understanding Information Technology"

#### Question 2

_________ = A * B * C

Product = A * B * C

#### Question 3

_________ = "15th August 1947"

Date\$ = "15th August 1947"

#### Question 4

_________ = 1/2 * A + 1/4 * B

Ans = 1/2 * A + 1/4 * B

#### Question 5

_________ = 11.99

Num = 11.99

## Define the following terms

#### Question 1

Variables

Variables are the assigned location in the memory used to store a value. This value can be changed at the time of execution of the program. A variable may be a single character or a set of characters. For example: A, B, B10, C\$ etc. are some valid variables.

Variables are of two types:

1. Numeric variables
2. Alphanumeric variables

#### Question 2

Constants

Constants are data values that do not change at the time of execution of the program. For example: 76, -43, "Hello", etc are some constants.

Constants are of two types:

1. Numeric constants
2. Alphanumeric constants

#### Question 3

Numeric variables

Numeric variables are the variables that store integer and fractional (decimal) values. The numeric variables are used to perform all arithmetical operations.
For example, P, A2, N1, etc. are some valid variables.

#### Question 4

Alphanumeric variables

Alphanumeric variables are used to store alphanumeric or string constants. The set of characters to be stored must be put within double quotes (" ").
For example, A\$, A1\$ etc. are some valid alphanumeric variables

#### Question 5

Alphanumeric constants

Any set of characters can be called a string or an alphanumeric constant. They also do not change their value at the time of execution of the program. It is a sequence of alphabets, digits and special characters enclosed within double quotes.
For example, "15th AUGUST, 1947", "April 4" etc. are some valid alphanumeric constants.

#### Question 6

Numeric constants

Numeric constants are the numbers comprising of digits 0-9. They are positive or negative numbers that may or may not have a decimal point. These constants are used for all kinds of mathematical operations.
For example, 543, -992, 298.543, -29.82, etc. are some valid numeric constants.

## Give two differences between

#### Question 1

Numeric constants and Alphanumeric constants

Numeric constantsAlphanumeric constants
Numeric constants comprise of digits.Alphanumeric constants comprise of a set of characters.
Numeric constants are not enclosed in double quotes.Alphanumeric constants are enclosed in double quotes.
For example, 12,54 etc.For example, "NEW DELHI - 110005", "BLOCK 2A" etc.

#### Question 2

Numeric variables and Alphanumeric variables