Project
on
VB Control Structures
Prepared By : Sudhir Kataria
PGT Computer Sc.
K V Chamera II
Detailed Lesson Plan
Project Summary



This project named “Control Structure” is mainly
focused on the working principle of various control
Structures in VB and their implementation in
Programming.
Various Practical Examples have been included in this
project relating to real life problems for the better
understanding of the concepts.
Programming questions, Output related questions are
formed so as to improve the logical & problem
solving ability of the students.
Learning Objectives






Working principles of various types of control
structures in VB.
Syntax & semantics of various statements in VB.
Implementation of Control structures in
Programming.
Connecting real-world entities using control
structures.
Solving real-life problems using control structures.
Enhancement of Logical & Problem solving ability of
the learner.
Assessment Procedures







Students performance will be judged/assessed by
inspecting the following factors :
Logic in Programming.
Efficiency & Effectiveness of Programs.
Usage of various control structures.
Correct syntax.
Correct code.
Following stylistic guidelines while programming i.e.
object naming conventions, meaningful object names,
proper indentation & spacing, prettyprinting style etc.
Implementation Procedures



Students will be explained about the working
principle of individual statement with the help
of its proper syntax and example.
After explaining working principle of every
statement, students will be given Practical
Examples, implemented using VB language on
Computer.
Students will be demonstrated the usage and
working of every statement in variety of ways,
according to the options available in the
syntax.
Implementation Procedures



Students will be given practical questions to
solve and implement using VB language.
After implementing every type of control
structure, students will be given a Home
Assignment based on the statements studied.
Students will be given a consolidated
Assignment in the end of the chapter so as to
test the logical ability of the children and their
understanding about the different types of
control structures and their implementation.
Resources Used




I am in teaching profession from last 12 years so this
complete lesson plan, assessment procedure,
programming questions, output related questions etc.,
are formed with my previous experience and
knowledge. Still I would like to mention few
resources I have used for the preparation of this
Project :
Text book of Informatics Practices by Sumita Arora.
Previous year CBSE Board question papers.
Computer.
VB Control Structures
Created By : Sudhir Kataria
PGT Computer Sc.
K V Chamera II
Control Flow




In a program, statements may be executed
sequentially, selectively or iteratively. Every
programming language provides constructs to
support sequence, selection or iteration. So
there are three types of programming
constructs :
Sequential Constructs
Selection Constructs
Iterative Constructs
Sequential Construct

The sequential construct means the statements
are being executed sequentially. This
represents the default flow of statements.
Stament 1
Stament 2
Stament 3
Selection Construct

The selection construct means the execution of
statement(s) depending upon the conditiontest. If a condition evaluates to true, a courseof-action (a set of statements) is followed
otherwise another course-of-action is followed.
This construct is also called decision construct
as it helps in decision making.
Selection Construct
One course-of-action
true
Condition
?
Statement 1
false
Statement 1
Statement 2
Another
courseof-action
Statement 2
Iterative Constructs

The iterative or repetitive constructs
means repetition of a set-of-statements
depending upon a condition-test. A set-ofstatements are repeated again and again
till the condition or Boolean Expression
evaluates to true. The iteration constructs
are also called as looping constructs.
Iterative Construct
false
The exit condition
Condition
?
True
Statement 1
Statement 2
The loop
body
Selection Constructs








VB provides two types of selection construct :
1) If statement
2) Select Case statement
The If Statement : If statement of VB comes in
various forms & are given below:
1) If..Then Statement
2) If..Then..Else Statement
3) If..Then..ElseIf Statement
4) Nested Ifs
If..Then Statement
Def. : An If..Then statement tests a particular
condition; if the condition evaluates to true, a
course-of-action is followed otherwise it is
ignored.
 Syntax :
If (boolean expression) Then
statements
End If

If..Then Statement
Example 1. :
If (Num>0) Then
Print “It is a positive number”
End if

Example 2 :
If txtAge.Text>=18 Then
Print “You are eligible to vote”
End if

If..Then..Else Statement
If..Then..Else statement provides an alternate choice
to the user i.e. if the condition is true then a set of
statements are executed otherwise another set of
statements are executed.
 Syntax :
If (boolean Expression) Then
VB Statement(s)
Else
VB Statement(s)
End If

Examples of If..Then..Else
Example 1 :
If txtAge.Text>=18 Then
Print “You are eligible to vote”
Else
Print “Sorry, You are not eligible to vote”
End If

Example 2 :
If Num Mod 2=0 Then
Print “It is an Even Number”
Else
Print “It is an Odd Number”
End If

If..Then..ElseIf Statement
If..Then..ElseIf statement is used to test a number of mutually
exclusive cases and only executes one set of statements for the
case that is true first.
 Syntax :
If (Boolean Expression) Then
Statement(s)
ElseIf (Boolean Expression 2) Then
Statement(s)
ElseIf (Boolean Expression 3) Then
Statement(s)
:
[ Else
Statement(s)
End If

Example of If..Then..ElseIf
If (Age<=4) Then
Print “Your rate is free.”
ElseIf (Age<=12) Then
Print “You qualify for the children’s rate.”
ElseIf (Age<65) Then
Print “You must pay full rate”
Else
Print “You qualify for the seniors’ rate.”
End If
Nested Ifs
A nested If is an if that has another If in its if’s body
or in its else’s body. The nested if can have one of the
following three forms :
1. If (expresssion 1) Then
If (expression 2 ) Then
Statement 1
[Else
Statement 2
End If
Else
body-of-else]
End If

Nested Ifs
2. If (expression 1) Then
body-of-if
Else
:
If (expression 2) Then
Statement-1
[Else
Statement-2]
End If
Nested If’s
3) If (expression 1) Then
:
If (expression 2) Then
Statement-1
[Else
Statement-2]
End If
Else
If (expression 3) Then
Statement-3
[Else
Statement-4]
:
End If
End If

Example of Nested If’s
If Num>0 Then
Print “It is a positive number”
Else
If Num<0 Then
Print “It is a negative number”
Else
Print “The number is equal to zero”
End If
End If
Select-Case Statement

Select-Case is a multiple branching statement
and is used to executed a set of statements
depending upon the value of the expression. It
is better to use Select-Case statement in
comparison to If..Then..ElseIf Statement when
the number of checks are more. There are 3
different forms of using Select-Case statements
and are given below :
Different forms of Select-Case
1. Select Case : Simplest Form [Exact match]
Select Case Expression
Case Value
’one or more visual basic statements
Case Value
’one or more visual basic statements
Case Else :
’one or more visual basic statements
End Select
Example of Form 1
Select Case byMonth
Case 1,3,5,7,8,10,12
number_of_days=31
Case 2
number_of_days=28
Case 4,6,9,11
number_of_days=30
End Select
Syntax of Form 2
Select Case : Second Form [Relational Test]
Select Case Expression
Case is relation :
’one or more visual basic statements
Case is relation :
’one or more visual basic statements
[Case Else :
’one or more visual basic statements
End Select
Example of Form 2
Select Case marks
Case Is < 50
Result = “Fail”
Case Is < 60
Result = “Grade B”
Case Is < 75
Result = “Grade A”
Case Else
Result = “Grade A+”
End Select
Third Form of Select Case
Select Case : Third Format [Range Check]
Select Case Expression
Case exp1 To exp2:
’one or more visual basic statements
Case exp1 To exp2:
’one or more visual basic statements
[Case Else:
’one or more visual basic statements
End Select
Example of Form 3
Select Case Age
Case 2 to 4 : Print “PreNursery”
Case 4 to 6 : Print “Kindergarden”
Case 6 to 10 : Print “Primary”
Case Else : Print “Others”
End Select
Home Assignment 1



Write a program in VB to compare three no’s
and print the smallest number among these
no’s.
Write a program in VB to check the eligibilty
of a person to vote. Display a message “You
are eligible to vote” if the age of the person is
greater than or equal to 18 otherwise print
“Sorry! You are not eligible to vote”
Write a program to compare two no’s and then
print the square and cube of the larger number
among these no’s.
Home Assignment
Write a program to display the grade obtained
by the child according to the marks obtained
by him/her. Criteria for assigning the grades is
given below : If marks are
>=90 - Grade is A
<90 and >80 – Grade is B
<80 and >=70 – Grade is C
<70 and >=60 – Grade is D
<60 – Grade is E

Iterative Constructs (Looping
Structures)


1)
2)
Loop : A loop is said to be the set of
instructions which are repeated again and
again in a program.
Types of Loops in VB :
Sentinel-controlled Loop Structures : repeat
statements until a special value called sentinel
value (or the terminating value) is reached.
Counter-controlled Loop Structures : repeat
the set of statements until the value specified
by the counter variable is reached.
Looping Structures

1.
2.
3.
VB offers broadly following three types of
looping structures :
For..Next
Do Loop
a) Do While..Loop
b) Do..Loop While
c) Do Until..Loop
d) Do..Loop Until
While..Wend
For..Next Statement

This type of statement is used when the user
knows in advance how many times the loop is
going to be executed.

Syntax :
For <counter Variable>=<start_val> To <end_val> Step
<increment/Decrement Value>
‘ One or more VB Statements
Next <counter Variable>
Examples
Example 1 : Generate natural no’s from 1 to
100
For I = 1 To 100
Print I
Next I
 Example 2 : Generate first 20 even no’s.
For E = 2 to 40 Step 2
Print E
Next E

More Examples
Example 3 : Generate odd no’s from 100 to 30
in a list box.
For O = 99 to 31 Step -2
ListO.AddItem(O)
Next O
 Example 4 : Generate table of any number N.
For T = 1 To N
Print N; “*”; T; “=”; N*T
Next T

More Examples

Example 5 : Find factorial of a given number
N.
:
Fact=1
For I= 1 to N
Fact = Fact * I
Next I
Print “Factorial of ”; N; “=”; Fact
:
Home Assignment 2

1)
2)
3)
4)
Write Programs for the following problems :
To Generate all the natural no’s from 200 to
500.
To Generate the table of 10.
To Generate all the even no’s from 200 to
400 in reverse order.
To Print first 20 multiples of the number
input by the user.
Do..Loop Structures
Do While..Loop : Do While loop is an entry
controlled loop in which the condition is
placed at the entry point. This statement
executes the statements specified in the body
of the loop till the condition evaluates to true.
The loop may not be executed at all the if the
condition is initially false.
 Syntax :
Do While <condition or boolean expression>
‘ One or more VB Statements
Loop

Examples of Do While..Loop
Example 1 : Never executes loop
Dim A as Byte
A=10
Do While A>10
A=A-1
Loop
 Example 2 : Executes loop
Dim P as Byte
P=20
Do While P>5
P=P-2
Loop

Do..Loop While
Do Loop While is an exit controlled loop as
the condition is placed at exit point. The body
of the loop is going to be executed at least
once whether the condition evaluates to true or
false. Loop is executed as long as the result of
the condition remains true.
 Syntax :
Do
One or more VB Statements
Loop While <condition or Boolean Expression>

Examples
Example 1 :
Do
num = InputBox (“Enter a number”)
sum = sum + num
Loop While num < > 0
 Here the statements inside the loop will be
executed once no matter what the comparison
test evaluates to.

Do..Until Loop
Do Until loop is an entry controlled loop in which the
condition is placed at the entry point. This statement
executes the statements specified in the body of the
loop till the condition evaluates to false. The loop
may not be executed at all the if the condition is
initially true.
 Syntax :
Do Until <condition or boolean expression>
‘ One or more VB Statements
Loop

Examples of Do Until..Loop
Example 1 : Never executes loop
Dim A as Byte
A=10
Do Until A<10
A=A-1
Loop
 Example 2 : Executes loop
Dim P as Byte
P=20
Do Until P<5
P=P-2
Loop

Do..Loop Until
Do Loop Until is an exit controlled loop as the
condition is placed at exit point. The body of
the loop is going to be executed at least once
whether the condition evaluates to true or
false. Loop is executed as long as the result of
the condition remains false.
 Syntax :
Do
One or more VB Statements
Loop Until <condition or Boolean Expression>

Examples
Example 1 :
Do
num = InputBox (“Enter a number”)
sum = sum + num
Loop Until num = 0
 Here the statements inside the loop will be
executed once no matter what the comparison
test evaluates to.

While..Wend

While..Wend loop is functionally equivalent to
the Do While..Loop. It executes a set of VB
statements till the condition evaluates to true.
Syntax :
While <Condition>
one or more vb statements
Wend

Examples
Example 1 : Generate the sum of first 10
natural no’s
I=1
While I<=10
Sum = Sum + I
I=I+1
Wend
Print “Sum of 10 natural no’s = ” ; Sum

Nested Loops
A loop within another loop is called as Nested
Loop.
 Example :
For I = 1 to 5
For J = 1 To 3
Inner Loop
Print J
Outer Loop
Next J
Print
Next I

Working of Nested Loops


In nested loops the inner loop is executed
completely for one time execution of the outer
loop. In the Previous example the Inner Loop
will be executed three times for every
execution of the outer loop.
Nested loops are very useful when there is a
requirement to generate different kind of
patterns as output.
Examples

Example : Program to generate the output given below :
1
22
333
4444
55555
Sol :
For I = 1 To 5
For J = 1 To I
Print I;
Next J
Print
Next I

Home Assignment 3 – Nested Loops

1)
3)
Write programs to generate the following patterns :
1
2) 1 2 3 4 5
12
1234
123
123
1234
12
12345
1
A
AB
ABC
ABCD
Home Assignment 4 – Output
Related Questions
Specify the output of the following output related
questions, assume that variables are declared :
1) sum=0
2) sum = 0
For I = 1 To 4
p=2 : q=4
For J = 1 To 3
Do While p<=10
sum = sum + J
If p Mod 2 = 0 Then
Next J
sum = sum + p
Print “Sum = ”;sum
End If
Next I
p=p+1
Loop
Print sum

Output related questions
3) R=5 : S=3
Do
Print R, S
R=R+1
If R = 7 Then
Exit Do
End If
S=S+R
Loop While R <=10
4) M=2 : N=4
Do Until M>12
N=N+M
If M Mod 3 = 0 Then
N=N-M
Else
N=N+M
End If
M=M+1
Loop
Print M, N
Home Assignment - 5






Programming Questions : Develop programs for the
followings :
To generate the mirror image of the number entered
by the user.
To generate the prime numbers between 100 and 700.
To Check whether the number entered by the user is a
prime number or not.
To print first 30 multiples of the number entered by
the user.
To generate the factorial of the number input by the
user.
Home Assignment - 5





To generate the Fibonacci series upto first 15 terms
i.e. 0 1 1 2 3 5 8…………..
To find the sum of all the numbers divisible by 7
from 100 to 200.
To check whether the year entered by the user is leap
year or not.
To find and print the sum of digits of the number
entered by the user.
To find and print the product of digits of the number
accepted from the user.
Assessment Tools



Students will be given Programming problems,
output and error finding questions to test
whether they understood the various concepts
taught through this presentation.
Various parameters are used to check the
understanding of the concept and its
implementation in Programming.
All the parameters mention in the next slide
have their own importance, so all these
parameters needs to be checked by the Teacher
teaching Programming.
Assessment Tool
Parameter
Specify whether Remark
Logic
Correct/Incorrect
Effective
Yes/No
Efficient
Yes/No
Coding
Correct/Incorrect
Syntax
Correct/Incorrect
Following
Naming
Conventions
Yes/No