School of Business
Eastern Illinois University
Program Flowchart,
Pseudocode & Algorithm
development
Week 2:
Wednesday 1/22/2003
Friday 1/24/2003
© Abdou Illia, Spring 2003
Project 1

Exercise # 8, page 57
Bohl & Rynn’s textbook

Due date: February 3rd, 2003
2
Learning Objectives

Understand the relation between Algorithm and
Pseudocode or program flowchart

Draw flowcharts

Write pseudocodes
3
4
Recall form Class 2 & 3

Use of tools by analyst/programmer in SDLC

Design/Programming tools used for:
–
Specifying problem-solving logic
Example
Pseudocode:
English-language
statements that describe
the processing steps of a
program in paragraph
form.
START
READ EMPLOYEE DATA
COMPUTE GROSS PAY
COMPUTE DEDUCTIONS
COMPUTE NET PAY
WRITE EMPLOYEE PAYCHECK
STOP
Algorithm ?

Step-by-step procedure to solve a problem

An algorithm can be expressed using:
–
–
–

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A System Flowchart
A Program Flowchart
A Pseudocode, etc.
Any algorithm must meet the following
requirements:
–
–
Use operations from only a given set of basic operations
(+,-,/,*,<,>…)
Produce solution in a finite number of such operations
Example of algorithm (program flowchart)
Algorithm for determining salespersons’ pay
REGSALES = Regular sales amount
I
SALESALES = Reduced sales amount
REGCOM = Regular commission (6%)
SALESCOM = Sales commission (3%)
PAY = Total pay due
P
O
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7
Algorithm vocabulary
SYMBOLS
START
NAME
USE
Terminal interrupt
symbols
Terminal point (start,
stop, or break)
STOP
Input/Output symbol
Process symbol
Reading data from an input medium
or writing data to an output medium
Processing input data
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Algorithm vocabulary
SYMBOLS
NAME
USE
Flowline symbol
Sequence of operations and
direction of data flow
Decision symbol
Predefined-process
symbol
Decision-making operations
Operations specified elsewhere (not
in the current algorithm)
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Algorithm vocabulary
SYMBOLS
NAME
USE
Connector symbol
Exit to, or entry from, another
part of the Flowchart
Preparation symbol
Control operations: Set limit on
loop-control variables, Initialize
accumulators, etc.
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Algorithm vocabulary
Item
Meaning
Variables
Data items whose
values may change, or
vary during processing
Data
independence
Using Variables instead of
their specific values gives a
program the capacity to
perform processing on any
set of input data.
Assignment
statement
Statement that assign a
value (calculated or
not) to a variable
Constant
A value that doesn’t
change
Example
READ
REGSALES,
SALESALES
Comment
1) Variables names are placeholders for values
2) Variable names are chosen
by programmer
3) Names should be descriptive
READ
$1000,
$3000
REGCOM =
REGSALES
*.06
.06
The computer will
perform the calculation
first, and then, assign
the result to REGCOM
IFTHENELSE / DECISION SYMBOL
An Example
General form
:
READ
AMOUNT
:
NO
Is
Condition
True ?
NO
YES
Could be
many
processings,…
AMOUNT
DISCOUNT =
AMOUNT * .10
SUBBIL=
AMOUNT
SUBBIL =
AMOUNT –
DISCOUNT
Processing 2
:
:
YES
> 200 ?
Processing 1
Processing 3
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Could be many
processings,…
:
:
Exercise 1: Tuition bill Problem
12
Write the program flowchart to prepare a tuition bill.
The input will contain the student name, Social
Security Number, and total number of credits for
which the student has enrolled. The bill will contain
the student name, Social Security Number, and
computed tuition. Total credits of 10 or more indicate
that the student is full-time. Full-time students pay a
flat rate of $1000 for tuition. Total credits of less than
10 indicate that the student is part-time. Part-time
students pay $100 per credit for tuition.
Exercise 11 (Chapter 3)
(To be done in class)
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Exercise 1’s solution: (Part 1: System Flowchart)
(To be done in class)
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Exercise 1 solution: (Part 2: Program Flowchart)
Project 1
15
Write a program flowchart and
corresponding pseudocode to solve the
following problem: Assume the input for a
student is name, student number, and
three grades. Output the student name and
an S (Success) if the average of the three
grades is 65 or more. Otherwise (else),
output the student’s name, a U
(Unsuccess), and the number of additional
points needed for an S.
Exercise 2: Billing problem
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Exercise 11 (Chapter 2)
Look at the program flowchart on the next slide, and answer the following questions:
(a)
For what variables are values read as input ?
(b)
What variables’ values are output ?
(c)
What constants are used ?
(d)
Simulate the execution of this algorithm, assuming the values shown below are
read as input for the first four variables named.
NAME
Mrs. A. B. Wallace
ITEM
Blouse
QTY
3
PRICE
49.99
AMTOD
DISCOUNT
SUBBILL
TAXES
BILL
Exercise 2: Billing problem
Exercise 11 (Chapter 2)
START
READ NAME,
ITEM, QTY,
PRICE
AMTOD =
QTY * PRICE
DISCOUNT =
AMTOD * .10
SUBBILL =
AMTOD - DISCOUNT
TAXES =
SUBBILL * .05
BILL =
SUBBILL + TAXES
WRITE NAME,
ITEM, BILL
STOP
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Exercise 1 solution: Program Flowchart &
corresponding Pseudocode
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START
READ
NAME, SSN,
CREDITS
Pseudocode for Tuition problem
Start
NO
CREDITS
YES
≥ 10 ?
Read NAME, SSN, CREDITS
IF CREDITS >= 10 THEN
TUITION =
TUITION = 1000
TUITION = 1000
100 * CREDITS
ELSE
TUITION = 100 * CREDITS
WRITE
NAME, SSN, TUITION
ENDIF
Write NAME, SSN, TUITION
Stop
STOP
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Pseudocode

Other common way to represent algorithms

Similar to programming languages like Visual Basic but
–
Does not require strict rules as programming languages
Pseudocode for Tuition problem (see Slide12)
Start
Read NAME, SSN, CREDITS
IF CREDITS >= 10 THEN
UPPERCASE for variable names
TUITION = 1000
ELSE
TUITION = 100 * CREDITS
UPPERCASE for Reserved words
ENDIF
Write NAME, SSN, TUITION
Titlecase
Lowercase for non- reserved words
Stop
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Pseudocode
Pseudocode for Tuition problem (see Slide12)
Start
Read NAME, SSN, CREDITS
IF CREDITS >= 10 THEN
Use of indentation (i.e. clauses are
indented a few positions) for
clarity
TUITION = 1000
ELSE
TUITION = 100 * CREDITS
ENDIF
Write NAME, SSN, TUITION
Stop
Exercise 3: Weekly Payroll problem
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Exercise 19 (Chapter 4)
Construct a program flowchart and corresponding
pseudocode to solve the following problem: ABC company
needs a weekly payroll report for its salespeople. Input to
the program is a salesperson’s name, number, and weekly
sales. Output is the salesperson’s name, number, and pay.
Each salesperson receives a base pay of $300 as well as a
10% commission on his or her total sales up to and
including $500. Any sales over $500 merit a 15%
commission for the employee. (For example, if sales = $600,
then pay = $300 + $50 [or .10 * 500] + $15 [.15 * 100] =
$350). Use a DOWHILE loop and a counter to compute the
weekly payroll for exactly 20 employees.
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Exercise 3’s solution: (Part 1: System Flowchart)
NAME, NUM,
SALES
WEEKLY
PAYROLL
PROGRAM
NAME, NUM,
PAY
(To be done in class)
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Exercise 3 solution: (Part 2: Program Flowchart)
Exercise 3 solution: (Part 3: Pseudocode)
(To be done in class)
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Algorithm Development Process

Design verification, in order to:
–
–

Prevent errors from occurring
Detect and correct errors soon
Selection of Review Team members for:
–
–

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Informal design review or
Structured design review
Structured Design Review:
–
–
Selection of representative values of input (data normally expected,
extreme values, invalid data)
Following designed algorithms to determine what output are produce.
Summary Questions
1. Distinguish between Algorithm on the one
hand, and Program flowchart and Pseudocode
on the other hand. Discuss the relations
between the two.
2. (a) List the main keywords used in
Pseudocodes. (b) What control structures they
represent.
You should know how to design program logic
using Program Flowcharts & Pseudocodes
(Review Exercises 1,2,3 above & Exercise 15
Ch.4 and answer on page 339)
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