1. Fill in the blanks:
(a) A variable name must have
1 to 40 characters.
(b) A variable name must start with
an alphabet.
(c)
Keywords of QBASIC are not allowed to use as a variable name.
(d) A variable can be declared
implicitly and explicitly.
(e) Explicit declaration of variables is done with
DIM statements.
(f) A symbolic constant is a symbol or a variable name, which represents only
one value throughout the program.
(g) Data types of QBASIC are : numeric and
String.
(h) Different numeric data types of QBASIC are
sting, integer, single precision and double precision.
2. State true or false :
(a) Symbol "%" is used for integer variable. True
(b) A keyword can be used as a variable name. False
(c) One variable can store only one value at a time. True
(d) The string cannot be used in arithmetic calculations. True
(e) It is good practice to declare variables at the beginning of a program. True
(f) The legal range for integer data type is from -32,767 to 32,768. False
(h) 'DIM N AS INTEGER' is an example of explicit declaration of variable. True
3. Write whether the given variables are valid or invalid , give reasons, if invalid:
| Variables | Reasons |
|---|
| 1N$ | Invalid, because start with number. |
| N$ | Valid, because start with the alphabet. |
| N%1 | Invalid, because of type declaration in middle. |
| LET | Invalid, because LET is a keyword. |
| FIRST NAME | Invalid, because of its blank space. |
| FNAME | Valid, because it is a meaningful variable name. |
4. Find out whether the following assignments are valid or invalid. Give reasons if invalid:
| Variables | Reasons |
| N$=KATHMANDU | Invalid, because string data is not enclosed in double quotation mark. |
| N= Rs. 2000 | Invalid, because numeric data only consist digit. |
| %N=2000 | Invalid, because start with type declaration. |
| N1=2,000 | Invalid, because number with a comma. |
| SAL= "2000" | Invalid, because numeric variable with a string data. |
| N$= "Nepal" | Valid, because string data is enclosed in double quotation mark. |
| 1N=200 | Invalid, because variable name start with a digit. |
5. Answer the following questions:
(a) Define variables and constants with examples.
Answer: Variable: An identifier or reference or name for the memory address that holds data and can change its value during the execution of a program is called variable.
Example of variable: Countryname$ , Age etc.
Constant: Those values, which are remained fixed during the execution of a program is called constant.
Example of constant: Conuntryname$ = "NEPAL" and Age = 15 etc.
(b) Write any three rules of writing a variable name.
Answer: 3 rules for variable naming are as follows:
- A variable name must start with an alphabet ( A to Z or a to z).
- A variable name may have 1 to 40 characters in length.
- Reserved word or keyword of QBASIC are not allowed to use as a variable name.
(c) What are the different types of data supported by QBASIC? Explain in short with their declaration symbols and memory consumption.
Answer:
| Data Type | Declaration Symbol | Data Range | Memory Consumption |
|---|
| String | $ eg. N$ , N1$ | 0 to 32,767 Characters | 4 bytes for descriptor, 1 byte for each character in string |
| Integer | %
eg. N% , N1% | -32,768 to 32,767 | 2 bytes |
| Long Integer | &
eg. N&, N1& | -2,147,483,648 to 2,147,483,647 | 4 bytes |
| Single Precision | !
eg. N! , N1! | Accuracy up to 7 digits | 4 bytes |
| Double Precision | #
eg. N# , N1# | Accuracy up to 15 digits | 8 bytes |
(d) What is a string variable? Write statements to declare string variable implicitly and explicitly.
Answer: A string variable is a name or reference or memory location, which stores alphanumerix characters.
Implicit declaration of stiring Variable
Example: LET N$ = "NEPAL"
Explicit declaration of string ariable
Example: DIM First.Name As STRING
(e) What is variable declaration? Declare a string type of variable with an example.
Answer: The process of declaring a variable name, its type and size is called variable declaration.
There are two types of variable declaration.
Implicit declaration of stiring Variable
Example: LET N$ = "NEPAL"
Explicit declaration of string ariable
Example: DIM First.Name As STRING
(f) Why is explicit declaration of variables better than implicit declaration?
Answer: Explicit declaration of a variable is better than implicit declaration of it because it reduces the repetition of variable name.
(g) What is string constant? Give an example.
Answer: A text value that consists of alphabet, digits, symbols, and other special characters is called string constant. For example : "Rosebud School", " Happy Dashain 2080" etc.
6. Write down the programs for the following:
(a) To store three different numbers under three different variables then find their sum and average.
CLS
INPUT " Enter three different numbers" , A, B, C
SUM = A+B+C
AVG = SUM / 3
PRINT "Sum of three different numbers is " , SUM
PRINT " Average of three different numbers is ", AVG
END
(b)To store name, address and telephone number of a person. Print them on the screen.
CLS
INPUT “Enter name, address and telephone number” , N$, A$, TEL$
PRINT “NAME” , “ADDRESS” , “ TELEPHONE”
PRINT N$, A$, TEL$
END
(c) To find out the sum of cube of two different numbers
CLS
INPUT “ Enter any two different numbers” , A, B
SUM = A ^ 3 + B ^ 3
PRINT “ Sum of cube of two different numbers is” , SUM
END
(d) To find the volume of a cylinder where Vol = PI * r2*h. (Use PI = 3.14 as symbolic constant)
CLS
INPUT “ Enter the radius and height of cylinder” , R , H
CONST PI = 3.14
VOL = PI * R ^ 2 * H
PRINT “ Volume of Cylinder is ”, VOL
END
(e) To store two different numbers; then find sum, difference and product of the numbers.
CLS
INPUT “Enter any two different numbers ” , A , B
SUM = A + B
DIFF = A - B
PROD = A * B
PRINT “SUM” , “DIFFERENCE” , “PRODUCT”
PRINT SUM , DIFF , PROD
END
(f) To store three different strings using three variables and print the string after concatenation
CLS
INPUT "Enter three string : ";A$,B$,C$
ANS$=A$+B$+C$
PRINT " Three string after concatenation : ";ANS$
END
(g) To store a number in a numeric variables and to calculate 10%,20%, and 25% of number and print them
CLS
INPUT "Enter three string : ";N
A = (N * 10) / 100
B = (N * 20) / 100
C = (N * 25)/100
PRINT " 10% of number = ";A
PRINT "20% of number=";B
PRINT "25% of number=";C
END
