1. Chapter 3 Planning Your Solution
CMPF144 Introduction to Problem Solving and Basic Computer

2. Overview Communicating with the Computer
Organizing the Solution with Tools
Testing the Solution
Coding the Solution

3. Objectives List and describe development tools
Use problem analysis chart
Use interactivity chart
Use IPO chart
Use algorithms (flowcharts and pseudocode)
Describe importance of documentation

4. Communicating with Computer
We use programming language to communicate with a computer
Different type of programming language applies different syntax.
Syntax: the rules governing the computer operating system, language and application
Bug : Coding error in a computer program
Debugging: Process to find and correct the coding errors (bugs)

5. Organizing Solution with Tools
Four (4) categories of tools can be used to solve problems on a computer:
Problem Analysis Chart (PAC)
Interactivity Chart / Structure Chart
IPO Chart
Algorithm
Flowchart
pseudocode

6. Problem Analysis Chart (PAC)
Shows a beginning analysis of the problem
Programmer will try to understand and analyze requirements of the problem
Allows programmer to glean only facts from the problem
Separated into four (4) parts:
The given data
The required results
The processing that is required in the problem
A list of solution alternatives

7. Basic Structure of Problem Analysis Chart

8. Problem Analysis Chart for the Payroll Problem

9. Interactivity Chart / Structure Chart
Shows the overall layout or structure of the solution
Divide the processing identified into subtasks called modules
these modules are connected together to show the interaction of processing between modules
Each module contain tasks for one function, not more than 20 instructions
Example of function:
Enter data
Print result
calculate result

10. Interactivity Chart (Cont.)
All modules are being controlled by a Control or Main Module
The breakdown (in the format of chart) allows programmer to view a complex problem in a few simpler parts.

11. Example of Interactivity Chart
Do you know what are these symbols???
Triangle on upper left of box??
Circle in chart??
Diamond shape after Module2??

12. Basic Interactivity Chart for the Payroll Problem
The control module, read module, calculation module, and print module are BASIC to most programs.
From there, add other modules as needed along with the addition of processing symbols to show:
Duplicates
Decision
Repetition in a loop

13. Completed Interactivity Chart – The Payroll Problem

14. IPO Chart
Extends and organizes information in problem analysis chart (PAC)
Consists of four (4) main sections:
Input
Processing
Module reference
Output

15. Is the sequence logical?? Why??
IPO Chart (Cont.)
Shows more detail/information about:
What data items are input??
What processing takes place on each specific data??
What information is output??
Sequence of completing IPO Chart:
Output
Input
Processing
Is the sequence logical?? Why??

16. IPO Chart for the Payroll Problem

17. Algorithm Shows the sequence of instructions, which will form solution
A good algorithm’s criteria:
Instructions cannot assume anything
Cannot skip steps
Must be executable one step at a time
Must be 100% complete
Two types of algorithm representation:
Flowchart
Pseudocode

18. Flowchart
Graphical representation of algorithm, which shows the flow of the processing from the beginning to the end of a solution.
A flowchart always starts at the top of the page and flows to the bottom
There are flowchart symbols for use with various types of processing.

19. Flowchart Symbols

20. Flowchart Symbols (Cont.)

21. Flowchart - the Payroll Problem

22. Flowchart - Read Module in the Payroll Problem

23. Calc Module in the Payroll Problem
Flowchart –
Calc Module in the Payroll Problem

24. Flowchart and Pseudocode for Print Module in the Payroll Problem

25. Overall Flowchart - The Payroll Problem
How to simplify this flowchart??

26. Pseudocode Algorithm which is represented in simple English form
Each instruction is written on a separate line
Starts with “Start/Begin” and terminates with “End”
Keywords and instructions are written from top to bottom, with only ONE entry and ONE exit.
Groups of statements are formed into module, and each module is given a specific name (however, this is optional).

27. Pseudocode (Cont.) Important keywords:
A computer can receive information
Keyword: Read, Get
A computer can show information
Keyword: Display, Print, Write
A computer can perform arithmetic calculation

28. Pseudocode (Cont.) A computer can assign value to memory location
Keyword: Set, Initialize
A computer can compare two variables to decide which action to be taken
Keyword; IF….ELSE…..END_IF
A computer can repeat a group of action.
Keyword: WHILE…END_WHILE, REPEAT…..UNTIL

29. Overall Pseudocode – The Payroll Problem
Begin REPEAT Get Hours, PayRate GrossPay = Hours * PayRate Display GrossPay UNTIL NoMoreEmployee = True End

30. Exercise (1)
Try to organize solution for problem illustrated below, with the help of FOUR (4) tools that you have learnt in this chapter.
Build a program that read the value of the height, width and length of a box from the user and print its volume.

31. Exercise (2)
Try to organize solution for problem in pp.76, PROBLEMS, Q6 with the help of FOUR (4) tools that you have learnt in this chapter.

32. Documentation Consists of two main types: Internal documentation
External documentation

33. Internal Documentation
For programmers
Made up of remarks written with the instructions to explain what is being done in the computer program, so that it can b easily understood by other programmers
Example:
what is the main purpose of developing this program
What are the meaning of certain code blocks
Status of program development ??

34. External Documentation
For end users
Made up of manuals or help menus written about the solutions.
Example:
Tutorial which shows the steps to use program
Installation instruction
Help files ??

35. Testing the Solution
to make sure that the solution meets requirements of user
to check for errors in logic or in setup of the expressions and equations.
programmer selects test data (a set of values for input data)and works them through every step in the solution.
Example: to test expression X/Y
Test data for X and Y should be any numbers other than 1. WHY??

36. Coding the Solution
To be performed after the completion of analyzing problem and organizing the solution.
A process of converting algorithm into real program by using appropriate type of programming language
Python : to be covered in practical class