1. Introduction to Flowcharting

2. Objective A program can be divided into 3 parts: Input data
Processing data – Calculation, etc.
Output information/results
Calculation/
Processing
Input
Output

3. Arrows From Top to Bottom & from Left to Right Make turn Join together
NOTE: Lines/Arrows must always be horizontal or vertical
and never cross to avoid confusion

4. What is a Flowchart?
START
Display message “How many hours did you work?”
Read hours
Display message “How much do you get paid per hour?”
Read payRate
Multiply hours by payRate. Store result in grossPay.
Display grossPay
END
A flowchart is a diagram that depicts the “flow” of a program.
A diagram made up of symbols of various shapes connected by arrows.
Those symbols indicate either actions to be taken or decisions to be made.
It helps us planning & programming.
The figure shown here is a flowchart for a pay-calculating program.
NOTE: Like IPO charts, there should be nothing programming language specific, just use descriptive words, e.g. “Read” or “Display”

5. Four Flowchart Structures
Sequence (Today)
Decision
Case
Repetition

6. Sequence Structure A series of actions are performed in sequence
The pay-calculating example was a sequence flowchart.

7. Basic Flowchart Symbols
Rounded Rectangle
START
Display message “How many hours did you work?”
Read hours
Notice there are three types of symbols in this flowchart:
rounded rectangles
parallelograms
rectangles
Each symbol represents a different type of operation.
Display message “How much do you get paid per hour?”
Parallelogram
Read payRate
Multiply hours by payRate. Store result in grossPay.
Rectangle
Display grossPay
Rounded Rectangle
END

8. Terminals: Rounded Rectangles
START
Display message “How many hours did you work?”
Terminals
represented by rounded rectangles
indicate a starting or ending point
Only 1 of each allowed!
Read hours
Display message “How much do you get paid per hour?”
Read payRate
Multiply hours by payRate. Store result in grossPay.
START
Display grossPay
END
Terminal
END

9. I/O Operations: Parallelograms
START
Display message “How many hours did you work?”
Input/Output Operations
represented by parallelograms
indicate an input or output operation
Read hours
Display message “How much do you get paid per hour?”
Input/Output Operation
Read payRate
Multiply hours by payRate. Store result in grossPay.
Display message “How many hours did you work?”
Read hours
Display grossPay
END

10. Processing: Rectangles
START
Display message “How many hours did you work?”
Processes
represented by rectangles
indicates a process such as a mathematical computation or variable assignment (not definition)
Read hours
Display message “How much do you get paid per hour?”
Read payRate
Calculate grossPay as hours * payRate
Multiply hours by payRate. Store result in grossPay.
Process
Multiply hours by payRate. Store result in grossPay.
Set name to “Fred”
Display grossPay
END

11. Stepping Through the Flowchart
START
Display message “How many hours did you work?”
In the next seven slides we will step through each symbol in the flowchart. We will show the program output and the contents of the variables.
Read hours
Display message “How much do you get paid per hour?”
Read payRate
Multiply hours by payRate. Store result in grossPay.
Variable Contents: hours: ? payRate: ? grossPay: ?
Display grossPay
END

12. Stepping Through the Flowchart
START
Step 1: An Output Operation
Display message “How many hours did you work?”
Read hours
Screen Output
How many hours did you work?
Display message “How much do you get paid per hour?”
Read payRate
Multiply hours by payRate. Store result in grossPay.
Variable Contents: hours: ? payRate: ? grossPay: ?
Display grossPay
END

13. Stepping Through the Flowchart
START
Display message “How many hours did you work?”
Read hours
Step 2: An Input Operation
(User types 40)
How many hours did you work? 40
Display message “How much do you get paid per hour?”
Read payRate
Multiply hours by payRate. Store result in grossPay.
Variable Contents: hours: 40 payRate: ? grossPay: ?
The value 40 is stored in hours.
Display grossPay
END

14. Stepping Through the Flowchart
START
Display message “How many hours did you work?”
Read hours
Screen Output
How much do you get paid per hour?
Display message “How much do you get paid per hour?”
Step 3: An Output Operation
Read payRate
Multiply hours by payRate. Store result in grossPay.
Variable Contents: hours: 40 payRate: ? grossPay: ?
Display grossPay
END

15. Stepping Through the Flowchart
START
Display message “How many hours did you work?”
Read hours
How much do you get paid per hour? 20
Display message “How much do you get paid per hour?”
Read payRate
Step 4: Input Operation
(User types 20)
Multiply hours by payRate. Store result in grossPay.
Variable Contents: hours: 40 payRate: 20 grossPay: ?
Display grossPay
The value 20 is stored in payRate.
END

16. Stepping Through the Flowchart
START
Display message “How many hours did you work?”
Read hours
How much do you get paid per hour? 20
Display message “How much do you get paid per hour?”
Step 5: The product of hours times payRate is stored in grossPay
Read payRate
Multiply hours by payRate. Store result in grossPay.
Variable Contents: hours: 40 payRate: 20 grossPay: 800
Display grossPay
The value 800 is stored in grossPay.
END

17. Stepping Through the Flowchart
START
Display message “How many hours did you work?”
Read hours
Screen Output
Your gross pay is 800
Display message “How much do you get paid per hour?”
Read payRate
Multiply hours by payRate. Store result in grossPay.
Variable Contents: hours: 40 payRate: 20 grossPay: 800
Display grossPay
Step 6: An Output Operation
END

18. Connectors Sometimes a flowchart will not fit on one page.
A connector (represented by a small circle) allows you to connect two flowchart segments. A

19. Connectors
The “A” connector indicates that the second flowchart segment begins where the first segment ends.
If you needed multiple connectors, you would use different letters for each, e.g. “B”, “C”
Think of it as a “teleporter” A
START
END

20. Review What do each of the following symbols represent?
(Answer on next slide)

21. Review What do each of the following symbols represent? Terminal
Input/Output Operation
Process

22. Review Name the four flowchart structures. Sequence Decision
Repetition
Case
(Answer on next slide)