The document discusses iterations, modular programming, and flowcharts. It explains how to use dry run tables to evaluate a program's logic and output. It also describes how to represent repetitive processes and complex conditions using loops and modular structures in flowcharts. Breaking problems into smaller modules is an important part of the structured programming technique.

1. Understanding Iterations and Implementing
Modular Programming
Objectives
In this lesson, you will learn to:
Use the dry run table
Identify repetitive processes
Represent complex conditions and iterations by using
flowcharts
Break down a problem into modules
©NIIT PLT/Lesson 3/Slide 1 of 30

2. Understanding Iterations and Implementing
Modular Programming
Dry Run
Helps you to do a logic check
Understand the flow of control in a flowchart
Evaluate the output of the program with a set of
sample values
Provides a step by step evaluation of values in the
variables of the program
©NIIT PLT/Lesson 3/Slide 2 of 30

3. Understanding Iterations and Implementing
Modular Programming
Dry Run (Contd.)
Example
All candidates have to take three tests. A candidate is
selected for the interview round based on the scores of
all the three tests. The individual score in each test has
to be greater than 75 and the average score across the
three tests should be a minimum of 80. The call letter for
the interview is to be sent to candidates who have been
selected and a rejection letter is to be sent to the rest.
Represent the logic for the above process by using a
flowchart.
©NIIT PLT/Lesson 3/Slide 3 of 30

4. Understanding Iterations and Implementing
Modular Programming
Variables
Variable Data Type Variable Name
Employee Name character cName
Employee Address character cAddress
Telephone Number character cTelno
Counter numeric nCounter
©NIIT PLT/Lesson 3/Slide 4 of 30

5. Understanding Iterations and Implementing
Modular Programming
Flowchart to Select a Candidate
Start
Declare Variables
Accept Variables and
Calculate nAverage
Is
nAverage= 80 AND No Display “ Rejection
nTest1 75 AND letter to be sent”
nTest2 75 AND
nTest3 75 ?
Yes
Display “ Interview
call letter to be sent”
Stop
©NIIT PLT/Lesson 3/Slide 5 of 30

6. Understanding Iterations and Implementing
Modular Programming
Dry Run Table
S.No. nTest1 nTest2 nTest 3 nAverage Output
1. 95 90 88 91 Interview call letter to be sent.
2. 80 77 83 80 Interview call letter to be sent.
3. 90 92 74 85.33 Rejection letter to be sent.
4. 76 76 76 76 Rejection letter to be sent.
©NIIT PLT/Lesson 3/Slide 6 of 30

7. Understanding Iterations and Implementing
Modular Programming
Iteration
An important characteristic of a computer is its ability
to execute a series of instructions repeatedly
A loop is a sequence of instructions that will be
repeated more than once
A loop performs steps in a specified sequence
There are two types of loops:
Fixed loops where the number of repetitions is
known
Variable loops where the number of repetitions is
not known
©NIIT PLT/Lesson 3/Slide 7 of 30

8. Understanding Iterations and Implementing
Modular Programming
Example
Flowchart to Display the Sum of Ten Numbers
Start
numeric nNum,
nSum, nCounter
nCounter=0
nSum=0
Accept nNum
nSum=nSum+nNum
nCounter=nCounter+1
Yes Is No
nCounter10 ? Display nSum
Stop
©NIIT PLT/Lesson 3/Slide 8 of 30

9. Understanding Iterations and Implementing
Modular Programming
Dry Run Table
S. No. nNum nSum nCounter Output
1. - 0 0
2. 5 5 1
3. 12 17 2
4. 7 24 3
5. 6 30 4
6. 2 32 5
7. 10 42 6
8. 8 50 7
9. 3 53 8
10. 16 69 9
11. 4 73 10 73
©NIIT PLT/Lesson 3/Slide 9 of 30

10. Understanding Iterations and Implementing
Modular Programming
Example
You have been assigned the responsibility of generating
an address list of all the people working in your office.
For each person, you will need to accept the name,
address, and the telephone number and print a list
containing the collated details.
©NIIT PLT/Lesson 3/Slide 10 of 30

11. Understanding Iterations and Implementing
Modular Programming
Flowchart Segment to Display Employee
Details of 25 People
nCounter = 1
Is No
nCounter=25?
Yes Stop
Accept cName
Accept cAddress
Accept cTelno
Display cName,
cAddress, cTelno
nCounter=nCounter+
1
©NIIT PLT/Lesson 3/Slide 11 of 30

12. Understanding Iterations and Implementing
Modular Programming
Example
Let us look at the same example of preparing the test
performance report in the decision-making section again.
Now, apart from finding out whether a candidate has to
be sent a call letter or a rejection letter, we also have to
calculate the number of candidates who have been sent
interview call letters and the number of candidates who
have been sent rejection letters, using a flowchart.
©NIIT PLT/Lesson 3/Slide 12 of 30

13. Understanding Iterations and Implementing
Modular Programming
Flowchart to Calculate the Total Number of
Call Letters and Rejection Letters Sent
Start
Variable Declaration
Accept Values
Is
nAverage =80 AND No
nTest1 75 AND nTotReject=nTotReject+1
nTest2 75 AND
nTest3 75 ?
Yes
nTotSelect=nTotSelect+1
A B
©NIIT PLT/Lesson 3/Slide 13 of 30

14. Understanding Iterations and Implementing
Modular Programming
Flowchart to Calculate the Total Number of Call
Letters and Rejection Letters Sent (Contd.)
B
A
Display “Any more
candidates (Y/N)? ”
Accept cChoice
Is No
cChoice = “Y”?
Yes Display nTotSelect
Display nTotReject
Stop
©NIIT PLT/Lesson 3/Slide 14 of 30

15. Understanding Iterations and Implementing
Modular Programming
Dry Run Table
S. No. nTest1 nTest2 nTest2 nAverage Output
1. 95 90 88 91 nTotSelect is incremented by 1.
2. 80 77 83 80 nTotSelect is incremented by 1.
3. 90 92 74 85.33 nTotReject is incremented by 1.
4. 76 76 76 76 nTotReject is incremented by 1.
©NIIT PLT/Lesson 3/Slide 15 of 30

16. Understanding Iterations and Implementing
Modular Programming
Modular Approach to Programming
A program needs to be amended periodically to
respond to changing conditions or requirements
This encouraged programmers to adopt a more
disciplined approach to program writing.
The techniques that were adopted are known as
structured programming techniques.
Structured programming includes features that are
designed not only to solve the problem at hand but
also to make the logic clear to someone reading the
program
©NIIT PLT/Lesson 3/Slide 16 of 30

17. Understanding Iterations and Implementing
Modular Programming
Modular Approach to Programming (Contd.)
Long, continuous programs can be broken up into a
series of individual modules that are related to each
other in a specified manner.
Main
Program
Module1 Module2 Module3
©NIIT PLT/Lesson 3/Slide 17 of 30

18. Understanding Iterations and Implementing
Modular Programming
Flowchart to Show Modular Programming
Start
numeric nNum1, Add
nNum2, nNum3, nSum
nSum=nNum1 + nNum2
Accept nNum1, + nNum3
nNum2, nNum3
Return
Add
Display nSum
Stop
©NIIT PLT/Lesson 3/Slide 18 of 30

19. Understanding Iterations and Implementing
Modular Programming
Example
Accept the test scores for ten students and display their
individual averages. The scores of the students cannot
be negative.
The table shows the variables used in the flowchart.
Variable Data Type Variable Name
Student Name character cStudentName
Score of Test 1 numeric nTest1
Score of Test 2 numeric nTest2
Score of Test 3 numeric nTest3
Average of Test Scores numeric nAverage
©NIIT PLT/Lesson 3/Slide 19 of 30

20. Understanding Iterations and Implementing
Modular Programming
Flowchart to Calculate Average Marks of Ten
Students
Accept
Accept cStudentName
Accept
Average
Accept nTest1
Average nAverage=(nTest1+nTest2
Accept nTest2 +nTest3) / 3
Display cStudentName, Accept nTest3 Return
nAverage
Is
nTest1=0 AND Yes
nTest2=0 AND
nTest3=0 ?
Return
No
Display “Test score cannot
be less than zero”
©NIIT PLT/Lesson 3/Slide 20 of 30

21. Understanding Iterations and Implementing
Modular Programming
Example
The total expenditure on salaries for the month needs to
be calculated. As per company policy an employee
receives a minimum of $500. Depict the logic for
automating the task by using flowcharts.
Program Variables to be used are:
Variable Data Type Variable Name
Employee Code character cEmpCode
Employee salary numeric nSalary
Total salary numeric nTotSalary
Choice character cChoice
©NIIT PLT/Lesson 3/Slide 21 of 30

22. Understanding Iterations and Implementing
Modular Programming
Flowchart to Calculate Total Monthly Expenditure
on Salaries
Accept
Is No Summation
cChoice = “Y” ? Accept nSalary
Yes
nTotSalary=nTotSalary+nSalary
Is Yes
Accept nSalary =500 ?
Return Return
No
Summation Display”Salary cannot
be less than $500”
©NIIT PLT/Lesson 3/Slide 22 of 30

23. Understanding Iterations and Implementing
Modular Programming
Example
Dry Run
S. No. nSalary nTotSalary Output
1. - 0
2. 4500 4500
3. 5500 10000
4. 3400 13400
5. 5600 19000
6. 3000 22000
7. 5000 27000
8. 450 27000 Salary cannot be less than $500
9. 9000 36000
10. 8900 44900
11. 4500 49400 49400
©NIIT PLT/Lesson 3/Slide 23 of 30

24. Understanding Iterations and Implementing
Modular Programming
Problem Statement 3.P.1
Draw a flowchart to print the product of the first 10 even
numbers.
©NIIT PLT/Lesson 3/Slide 24 of 30

25. Understanding Iterations and Implementing
Modular Programming
Problem Statement 3.P.2
Draw a flowchart to accept 50 numbers and also display
the total number of odd and even numbers.
©NIIT PLT/Lesson 3/Slide 25 of 30

26. Understanding Iterations and Implementing
Modular Programming
Problem Statement 3.P.3
Draw a flowchart to display the highest of any 10
numbers entered.
©NIIT PLT/Lesson 3/Slide 26 of 30

27. Understanding Iterations and Implementing
Modular Programming
Problem Statement 3.P.4
Draw a flowchart that accepts input from a user and
displays the result, depending on whether the user
wishes to multiply or divide the numbers provided
as input. The Multiply module of the program can
multiply maximum of three numbers. The Divide
module of the program should check that the
denominator should not be zero.
©NIIT PLT/Lesson 3/Slide 27 of 30

28. Understanding Iterations and Implementing
Modular Programming
Problem Statement 3.P.5
How many names will the following flowchart print?
nCtr = 0
Accept cName
Display cName
No Is
nCtr =10 ?
Yes
Stop
©NIIT PLT/Lesson 3/Slide 28 of 30

29. Understanding Iterations and Implementing
Modular Programming
Summary
In this lesson, you learned that:
The concept of dry run will help you perform a logic
check and understand the flow of control in a
flowchart.
A loop is a sequence of instructions that will be
repeated more than once
A loop performs steps in a specified sequence
There are two types of loops:
® Fixed
loops where the number of repetitions is
known
©NIIT PLT/Lesson 3/Slide 29 of 30

30. Understanding Iterations and Implementing
Modular Programming
Summary (Contd.)
® Variable loops where the number of repetitions is not
known
Statements within a loop will be executed repeatedly
until the condition becomes false
The structured programming technique is a disciplined
approach to program writing.
A large program can be divided into several modules,
where each module performs a specific task. A module
is also called a procedure.
A procedure or a module is invoked from the main
program and the control is returned from the procedure to
the main program by using the return statement
©NIIT PLT/Lesson 3/Slide 30 of 30