Fundamentals of QBASIC: Constants and Variables
Choose the correct option
Question 1
Which of the following is not a valid numeric constant?
- -325
- -99.99
- $24
- 0.00025
Answer
$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?
- AB$
- AB$$
- $AB$
- $$AB
Answer
AB$
Reason — String variables must end with a $ sign.
Question 3
Which of the following is a valid string constant?
- Computer Science
- 'Computer Science'
- "Year - 2022"
- !!Computer!!
Answer
"Year - 2022"
Reason — String constants are always enclosed in double quotes ("").
Question 4
Which of the following statements is correct for numeric variables?
- They cannot store numbers.
- They are used for mathematical operations.
- They begin with a dollar sign.
- They can store string constant.
Answer
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?
- Negative numbers cannot be assigned to a variable.
- Only positive numbers can be assigned to a variable.
- Numeric constant can only be assigned to numeric variables.
- Numeric variables are assigned to numeric constants.
Answer
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 ($) sign.
Question 2
Numeric constants include only numbers.
Question 3
The maximum length of a variable is 12.
Question 4
Alphanumeric constants are always enclosed in double quotes.
Question 5
Variables always begin with alphabets.
Question 6
A comma is not allowed while writing numeric constants.
State True or False
Question 1
A45 is a valid numeric variable.
True
Question 2
A+B is not a valid alphanumeric variable.
True
Question 3
Special characters are used in variables.
False
Question 4
Numeric constants are stored in numeric variables.
True
Question 5
0.5495 is a valid numeric constant.
True
Question 6
Decimals are not allowed in numeric constants.
False
Match the following
Question 1
Sl. No. | Column 1 | Column 2 |
---|---|---|
1 | Numeric constants | Alphanumeric constants |
2 | Alphanumeric variables represent | are always enclosed in " " |
3 | Alphanumeric constants | must begin with an alphabet |
4 | A variable | String variables |
5 | Alphanumeric variables are called | can take part in mathematical operations |
Answer
Sl. No. | Column 1 | Column 2 |
---|---|---|
1 | Numeric constants | can take part in mathematical operations |
2 | Alphanumeric variables represent | Alphanumeric constants |
3 | Alphanumeric constants | are always enclosed in " " |
4 | A variable | must begin with an alphabet |
5 | Alphanumeric variables are called | String variables |
Name the following
Question 1
Two types of variables
Answer
- Numeric variables
- Alphanumeric variables
Question 2
Two types of constants
Answer
- Numeric constants
- Alphanumeric constants
Correct the following statements
Question 1
B$ = WORLD CUP 2007
Answer
B$ = "WORLD CUP 2007"
Question 2
"DELHI PUBLIC SCHOOL" = D$
Answer
D$ = "DELHI PUBLIC SCHOOL"
Question 3
$$
A = "ARYA PUBLISHING COMPANY"
Answer
A$ = "ARYA PUBLISHING COMPANY"
Question 4
P$ = (A + B)2
Answer
P = (A + B) ^ 2
Question 5
4B$ = "NEW DELHI"
Answer
B4$ = "NEW DELHI"
Question 6
A = 4P + 5Q
Answer
A = 4 * P + 5 * Q
Question 7
AVG = (2A + 3B + 4C)/3
Answer
AVG = (2 * A + 3 * B + 4 * C) / 3
Question 8
A*B = AB + CD
Answer
AB = A * B + C * D
Write down the appropriate variables for the following
Question 1
_________ = "Understanding Information Technology"
Answer
UIT$ = "Understanding Information Technology"
Question 2
_________ = A * B * C
Answer
Product = A * B * C
Question 3
_________ = "15th August 1947"
Answer
Date$ = "15th August 1947"
Question 4
_________ = 1/2 * A + 1/4 * B
Answer
Ans = 1/2 * A + 1/4 * B
Question 5
_________ = 11.99
Answer
Num = 11.99
Define the following terms
Question 1
Variables
Answer
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:
- Numeric variables
- Alphanumeric variables
Question 2
Constants
Answer
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:
- Numeric constants
- Alphanumeric constants
Question 3
Numeric variables
Answer
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
Answer
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
Answer
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
Answer
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
Answer
Numeric constants | Alphanumeric 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
Answer
Numeric variables | Alphanumeric variables |
---|---|
Numeric variables store numeric values. | Alphanumeric variables store alphabets, words, special characters or their combinations. |
These variables must begin with an alphabet, alphabets or alphabets followed by a number. | These variables begin with an alphabet or alphabets but must end with a dollar sign. |
These variables are used for mathematical operations. | Mathematical operations are not possible. |
For example, A, ABC, etc. | For example, A$, B12$ etc. |