Chapter 1 :Algorithm and Flowchart
#Algorithm
1. Write an algorithm to eat your dinner.
2. Write an algorithm to buy a pen.
3. Write an algorithm to turn on the computer.
4. Write an algorithm to download an application(app) on mobile phone.
5. Write an algorithm to stay for online classes.
1. Write an algorithm to add 10 and 20
Step 1: Start
Step 2: a=10, b=20
Step 3: sum= a+b
Step 4: Print sum
Step 5: End
2. Write an algorithm to add two numbers
Step 1: Start
Step 2: Input a,b
Step 3: sum= a+b
Step 4: Print sum
Step 5: End
3. Write an algorithm to subtract three numbers.
Step 1: Start
Step 2: Input a,b and c
Step 3: difference= a-b-c
Step 4: Print difference
Step 5: End
Step 1: Start
Step 2: Input a and b
Step 3: product= a*b
Step 4: Print product
Step 5: End
Step 1: Start
Step 2: Input a and b
Step 3: divide= a/b
Step 4: Print divide
Step 5: End
6.Write an algorithm to find area of square (hint: area of square=L*L)
Step 1: Start
Step 2: Input L
Step 3:area of square= L*L
Step 4: Print area of square
Step 5: End
7.Write an algorithm to find area of rectangle (hint: area of rectangle=L*b)
Step 1: Start
Step 2: Input L and b
Step 3:area of rectangle= L*b
Step 4: Print area of rectangle
Step 5: End
8. Write an algorithm to find area of circle.(hint: area of circle=3.14*r*r)
Step 1: Start
Step 2: Input r
Step 3:area of circle=3.14*r*r
Step 4: Print area of circle
Step 5: End
Step 1: Start
Step 2: Input L
Step 3:perimeter of square=4*L
Step 4: Print perimeter of square
Step 5: End
10. Write an algorithm to find perimeter of rectangle.(hint: area of square=2*(L+b)
Step 1: Start
Step 2: Input L abd b
Step 3:perimeter of rectangle=2*(L+b)
Step 4: Print perimeter of rectangle
Step 5: End
11. Write an algorithm to find out greatest of any three given number.
Step 1: start
Step 2:Input a, b and c
Step 3: if a>b and a>c then
Step 4: Print a is greatest else b>c and b>a
Step 5: Print b is greatest else Print c is greatest
Step 6: Stop
Step 2:Input L,b and h
Step 3:volume=L*b*h
Step 4: Print volume
Step 2:Input m
Step 3:c= m*100
Step 4: Print c
Step 2:Input x, y and z
Step 3:average=(x+y+z)/3
Step 4: Print average
Flowchart
A flowchart can also be defined as a diagrammatic representation of an algorithm.
The flowchart shows the steps as boxes of various kinds, and their order by connecting the boxes with arrows.
1. Draw a flowchart to add 10 and 20.
4. Draw a flowchart to take input from user and subtract those number.
5. Draw a flowchart to find area of square.
6. Draw a flowchart to find area of circle.
7. Draw a flowchart to find perimeter of rectangle.
8. Draw a flowchart to find perimeter of square.
9. Draw a flowchart to find volume of cube.
10.Draw a flowchart to find volume of cuboid.
11.Draw a flowchart to take input from user and find whether the number is odd or even.
12.Draw a flowchart to take input from user and find greatest among two numbers.
Answer the following questions.
What is a program?
A set of instructions that tells the computer how to solve a problem or perform a task is known as a program.
What is an algorithm? List out any three properties of an algorithm.
algorithm has the following properties:
Each step of the algorithm should be simple.
The logic of each step should be clear.
It should be effective.
An algorithm must come to an end after a finite number of steps.
Every step of the algorithm must be accurate. At the same time, it must have a time limit for execution.
The output must be logically correct.
What are the advantages of an algorithm?
They are simple to understand and provide a step-by-step solution for a problem.
Errors can be pointed out very easily. Debugging is simple.
They do not depend on any of the programming languages.
They are compatible with computer languages.
What are the disadvantages of an algorithm?
Disadvantages
Algorithms are time-consuming.
Big tasks are difficult to put in algorithms.
Difficult to show branching and looping in algorithms.
Understanding complex logic through algorithms can be very difficult.
What do you understand by the term flowchart?
State any three advantages and disadvantages of a flowchart.
advantages
It helps in reviewing and debugging a program.
It helps to detect deficiencies in the problem statement.
It helps the programmer in developing the program logic and to serve as documentation for future reference for a completed program.
It helps in the discussion of a solution with others or in explaining the program to others.
Disadvantages
Drawing a flowchart is time consuming.
Making changes in the flowchart is not an easy job. Re-drawing of flowchart is required.
If the logic of the problem is complex, the flowchart becomes complicated.
Flowchart cannot be directly converted into program code.
What are the various basic symbols used in flowcharting? Give their pictorial representation.
What is a pseudocode? What are the advantages and disadvantages of pseudocode?
An informal language used to express the flow of a program is known as pseudo code.
The advantages of pseudocode are listed below:
Writing of pseudocode involves less time and effort than drawing an equivalent flowchart
It can be easily modified.
Converting a pseudocode to a programming language is much easier than converting a flowchart to a programming language.
The disadvantages of pseudocode are listed below
It becomes difficult to understand the complex logic written in pseudocode.
When too many nested conditions are used in the pseudocode, the level of difficulty to understand the code increases.
In the case of pseudocode, a pictorial representation of program logic is not available.
Fill in the blanks
The instructions to the computer are given in the form of a ………..….. to carry out a specific task.
………..….. is a set of step by step instructions given in a logical order to solve a problem.
………..….. is a graphical representation of an algorithm.
………..….. box is used to show the steps involving comparison and decision making steps.
………..….. is an artificial and informal language that helps programmers develop algorithms.
State whether the following statements are True or False.
Algorithm consists of a standard set of symbols of different shapes which are connected by arrows.
The flowchart helps in the discussion of a solution with others or in explaining the program to others.
Decision box indicates any calculation or manipulation.
Connectors are used to connect the flowchart symbols.
Chapter 2 :Qbasic
Introduction to QBASIC
BASIC stands for 'Beginners All Purpose Symbolic Instruction code'. It was founded in 1963 at Dartmouth college, by the mathematicians John George Kemeny and Tom Kurtzas.
BASIC is an Interpreter.
Q stands for 'Quick'
QBASIC- Quick Beginners All Purpose Symbolic Instruction code
Features of QBASIC
(a) It is easy to understand the language and write programs using it.
(b) The words used in it are similar to the English words used in daily life like LET, INPUT, PRINT etc.
(c) Many tasks can be done easily from the menus available in it.
(d) If there are any mistakes while writing the program, it can be easily corrected.
(e) It can be used to write a program, view its output and correct mistakes using more than one window.
(f) Help can be used as required.
Elements of Qbasic programming
Character set
Variables
Constants
Operator and operand
Expression
Statement
Character set
Character set refers to the letters, numbers, and groups of different symbols that can be used in QBASIC. The Character set used in QBASIC is divided into the following three groups:
(a) Letters: A to Z (small and capital letters)
(b) Numbers: 0 to 9
(c) Special symbols: =, +, *, -, /, ^, $, <>, (),%, #,!, &,? Etc.
Variables
The names used to represent the various digits, letters, and values used in the program, Variables represent a specific area of memory, in which the stored values can be changed as needed. It is of two types.
(a) Numeric variables
(b) String variables
(a)Numeric variables
The variables used to store numbers are called numeric variables. For example: x = 5, Age = 15, Salary = 15000 etc. Here x, Age / Salary can store numbers, which are called Numeric variables. Mathematical operations can be done on numeric variables like addition, subtraction, multiplication, division etc.
(b)String variables
Variables representing the letters or groups of characters used in the program are called string variables. String variables are used to store a person's name, address, etc.
For example:
name$ = "Ram",
address$ = "Nepal",
Here name$ and address$ are called string variables. If the string variables have an '$' sign at the end, the value to be stored in it is written inside.
Constants
The various numbers or letters used in a program that do not change when the program is run are called constants. There are two types of constants:
(a) Numeric constants
(b) String constants
(a) Numeric constants
Numeric constants positive) or negative numbers, in which mathematical operations can be added, subtracted, multiplied, divided, etc., are called numeric constants, such as 5,19,0,9.8 etc. are numeric constants. The comma (,) and blank spaces cannot be placed in the numeric constant.
(b) String constants
A group of different numbers or letters used in a program that are placed within a quotation mark ("") are called string constants, such as: "good morning", "01-5246610", "A215", etc. Blank spaces or any other symbols can be used in string constant. Mathematical operations like addition, subtraction, multiplication, division etc. cannot be performed on a string constant.
Operators and operands
In the programming language, various signs or symbols used to perform mathematical or other tasks are called operators. For example: '+' to add, '-' to subtract. Operators that work on values That is called operand.
E.g. 5 *3
5 and 3 is operand
* is operator
Expression
Expressions are written to do certain things with the help of different operators and operands. The algebraic expressions we write in our daily lives cannot be understood in the same way as QBASIC. Therefore, the table to convert algebraic expression to QBASIC expression is presented in the following examples:
Statements
The instructions used in the program to perform certain tasks are called statements. When writing a program using any programming language, you have to write statements following certain rules of that language. The statements written in the QBASIC program are first stored in the computer's memory and only after running the program do they show certain results.
Statement of Qbasic are
Rem
CLS
Let
Input
Rem
REM statement is a non-executable statement and stands for remarks.
CLS
CLS statement is used to clear the output screen.
Input
It helps to take input from user. we will take it only as an alphabet (a,b,c,d,..........)
e.g.- Input "Enter a number"; a
Input "Enter your name"; a$
Using Print tag we can print anything we want in our output screen.
e.g.- Print "My school's name is Manaslu School"
END
END statement is used to end the program execution
1. Write a Qbasic program to find sum of two numbers
Rem to find sum of two numbers
CLS
Let A=12
Let B=8
Let C=A+B
Print “Sum=”;C
END
Output: Sum=20
2. Write a Qbasic program to find area of rectangular room
Rem to find area of room
CLS
Let L=12
Let B=10
Let A=L*B
Print “Area of room=”;A
END
Output: Area of room=120
3. Write a Qbasic program to read the value of radius and find area of circle
Rem to find area of circle
CLS
Input “Enter radius of circle=”;R
Let Area=3.14*R*R
Print “Area of circle=”;Area
END
Output Enter radius of circle= 8
Area of circle=200.96
4. Write a Qbasic program to read three numbers and find average of three numbers
Rem to find average of three numbers
CLS
Input “Enter first number=”;a
Input “Enter second number=”;b
Input “Enter third number=”;c
Let Average= (a+b+c)/3
Print “Average=”; Average
END
Output Enter first number= 10
Enter second number=8
Enter third number= 5
Average=7.67
Rem to find average of two numbers
CLS
Input “Enter first number=”;a
Input “Enter second number=”;b
Let Average= (a+b)/2
Print “Average=”; Average
END
Output Enter first number= 10
Enter second number=8
Average=9
5. Write a Qbasic program to read name, address and age and display it.
Rem to display name, address and age
CLS
Input “Enter your name:”;a$
Input “Enter your address:”;b$
Input “Enter your age:”;c
Print “Name-”;a$
Print “address:”;b$
Print “age:”;c
END
Output Enter your name: Ram
Enter your address: Nayabazar
Enter your age:15
Name-Ram
Address: Nayabazar
Age:15
END
Convert following algebraic expressions into Qbasic expression:
2xy
Ans:2*x*y
a²+b²
Ans:a^2+b^2
I= PTR/100
Ans:I=(P*T*R)/100
y=mx+c
Ans:y=m*x+c
A=r²
Ans:A=r^2
Write down the output of the following programs.
1.Rem to find product of two numbers
CLS
LET M=7
LET N=5
LET P=M*N
PRINT "Product of two numbers = ", P
END
Ans:Output: Product of two numbers =35
2.REM to increase value of a variable by 15%
CLS
LET A = 100
LET A=A+ A * 15/100
PRINT "New value of A="A
END
Ans: Output: New value of A=115
3.Remark to subtract two numbers
CLS
LET A = 20
Let B=10
C=A-B
PRINT "Difference between two numbers=”; C
END
Ans:Output: Difference between two numbers=10
4.Rem to print name and age
CLS
Age = 13
Name$ = "Sundar"
PRINT "Name is : ", Name$
DISPLAY "Age is: ", Age
END
Ans:Output: Name is :Sundar
Age is: 13
Write a Qbasic program
(A)To show the name, address and total number of students in your class.
Rem to display name, address and total number of students in my class.
CLS
Input “Enter your name:”;a$
Input “Enter your address:”;b$
Input “Enter total number of students in your class.:”;c
Print “Name-”;a$
Print “address:”;b$
Print “total number of students in your class:”;c
END
Output:
Name-Urgen Bal
address: Nayabazar
total number of students in your class: 42
(B) To find simple interest (I=PTR / 100)
Rem to find simple interest
CLS
Input “Enter principle:”;P
Input “Enter time:”;T
Input “Enter Rate”;R
Let I=(P*T*R)/100
Print “Simple interest=”;I
END
Output:
Enter principle:1000
Enter time: 2
Enter Rate: 10
Simple interest=200
(c) To convert rupee into paisa
Rem to convert rupee into paisa
CLS
Input “Enter rupee:”;r
Let a=r*100
Print “paisa=”;a
END
output
Enter rupee: 12
paisa=1200
(D) To convert a given temperature in centigrade to Fahrenheit (F = 9C / 5 + 32)
Rem to convert a given temperature in centigrade to Fahrenheit
CLS
Input “centigrade: ”;c
Let F=c * (9 / 5) + 32
Print “Fahrenheit =”;F
END
OUTPUT:
centigrade: 32
Fahrenheit =89.6
(E) To find the average of any three numbers.
(F) To take a number and print it square (if 5 is given 25)
Rem to take a number and print it square
CLS
Input “Enter a number: ”;a
Let X=a*a
Print “square =”;X
END
Output:
Enter a number: 7
square = 49
(G)To Find the perimeter of a circle.(P=2πr)
(H) To find the volume of a wax (V = LxBxH)
(I) To find out the value of an item and add 13% value added tax (VAT) to its total value.
REM to add VAT 13%
CLS
Input”Enter a number=”;a
LET C=a+ a* 13/100
PRINT "VAT="C
END
Output
Enter a number=100
VAT=113
Revision Questions
What is a flowchart? Draw symbols used in flowchart and write its functions.
Draw a flowchart to find sum of any five positive numbers
Write an algorithm and draw a flowchart to find greatest among any four different numbers.
Difference between algorithm and flowchart
Write a Qbasic program to read value of base and height of a triangle and find its area
Explain function of PRINT, LET
What is a computer?
Explain characteristics of computer?
What is CPU?
Explain function of computer briefly.
What are demerits of computer?
What is hardware?
Define software with any four examples.
Difference between input and output devices
Explain function of PRINT, LET, INPUT
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