1. Program Flowchart, Pseudocode & Algorithm development
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

2. Project 1 Exercise # 8, page 57 Bohl & Rynn’s textbook
Due date: February 3rd, 2003

3. Learning Objectives
Understand the relation between Algorithm and Pseudocode or program flowchart
Draw flowcharts
Write pseudocodes

4. Recall form Class 2 & 3 Use of tools by analyst/programmer in SDLC
Design/Programming tools used for:
Specifying problem-solving logic
START
READ EMPLOYEE DATA
COMPUTE GROSS PAY
COMPUTE DEDUCTIONS COMPUTE NET PAY
WRITE EMPLOYEE PAYCHECK
STOP
Example
Pseudocode:
English-language statements that describe the processing steps of a program in paragraph form.

5. Algorithm ? Step-by-step procedure to solve a problem
An algorithm can be expressed using:
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

6. Example of algorithm (program flowchart)
Algorithm for determining salespersons’ pay I
REGSALES = Regular sales amount
SALESALES = Reduced sales amount
REGCOM = Regular commission (6%)
SALESCOM = Sales commission (3%)
PAY = Total pay due P O

7. Algorithm vocabulary SYMBOLS NAME USE START STOP
Terminal interrupt symbols
Terminal point (start, stop, or break)
STOP
Reading data from an input medium or writing data to an output medium
Input/Output symbol
Process symbol
Processing input data

8. Algorithm vocabulary SYMBOLS NAME USE Flowline symbol
Sequence of operations and direction of data flow
Decision symbol
Decision-making operations
Predefined-process symbol
Operations specified elsewhere (not in the current algorithm)

9. 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.

10. Algorithm vocabulary Item Meaning Example Comment Variables
1) Variables names are place-holders for values
2) Variable names are chosen by programmer
3) Names should be descriptive
Data items whose values may change, or vary during processing
Variables
READ
REGSALES,
SALESALES
Using Variables instead of their specific values gives a program the capacity to perform processing on any set of input data.
Data independence
READ
$1000,
$3000
Assignment statement
Statement that assign a value (calculated or not) to a variable
The computer will perform the calculation first, and then, assign the result to REGCOM
REGCOM =
REGSALES
*.06
Constant
A value that doesn’t change
.06

11. IFTHENELSE / DECISION SYMBOL
General form
An Example :
READ
AMOUNT Is
Condition
True ?
AMOUNT
> 200 ? NO
YES NO
YES
Processing 1
DISCOUNT =
AMOUNT * .10
Processing 3
SUBBIL=
AMOUNT
Could be many processings,…
Processing 2
SUBBIL =
AMOUNT –
DISCOUNT
Could be many processings,… : :

12. Exercise 1: Tuition bill Problem
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)

13. Exercise 1’s solution: (Part 1: System Flowchart)
(To be done in class)

14. Exercise 1 solution: (Part 2: Program Flowchart)
(To be done in class)

15. Project 1
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.

16. Exercise 2: Billing problem
Exercise 11 (Chapter 2)
Look at the program flowchart on the next slide, and answer the following questions:
For what variables are values read as input ?
What variables’ values are output ?
What constants are used ?
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

17. 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

18. Exercise 1 solution: Program Flowchart & corresponding Pseudocode
START
READ
NAME, SSN, CREDITS
Pseudocode for Tuition problem
Start
Read NAME, SSN, CREDITS
IF CREDITS >= 10 THEN
TUITION = 1000
ELSE
TUITION = 100 * CREDITS
ENDIF
Write NAME, SSN, TUITION
Stop
CREDITS
≥ 10 ? NO
YES
TUITION =
100 * CREDITS
TUITION = 1000
WRITE
NAME, SSN, TUITION
STOP

19. Pseudocode for Tuition problem (see Slide12)
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
TUITION = 1000
ELSE
TUITION = 100 * CREDITS
ENDIF
Write NAME, SSN, TUITION
Stop
UPPERCASE for variable names
UPPERCASE for Reserved words
Titlecase
Lowercase for non- reserved words

20. Pseudocode for Tuition problem (see Slide12)
Start
Read NAME, SSN, CREDITS
IF CREDITS >= 10 THEN
TUITION = 1000
ELSE
TUITION = 100 * CREDITS
ENDIF
Write NAME, SSN, TUITION
Stop
Use of indentation (i.e. clauses are indented a few positions) for clarity

21. Exercise 3: Weekly Payroll problem
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.

22. Exercise 3’s solution: (Part 1: System Flowchart)
NAME, NUM, SALES
WEEKLY PAYROLL PROGRAM
NAME, NUM, PAY

23. Exercise 3 solution: (Part 2: Program Flowchart)
(To be done in class)

24. Exercise 3 solution: (Part 3: Pseudocode)
(To be done in class)

25. Algorithm Development Process
Design verification, in order to:
Prevent errors from occurring
Detect and correct errors soon
Selection of Review Team members for:
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.

26. 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)