1. Writing Pseudocode And Making a Flow Chart A Number Guessing Game
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Writing Pseudocode
And
Making a Flow Chart
Instructor: Richard T. Vannoy II
Copyright 2004, Richard T. Vannoy II

2. Learning Objectives To read a word problem and create:
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To read a word problem and create:
Correct Pseudocode, and
An accurate flow chart
Copyright 2004, Richard T. Vannoy II

3. The Problem: The problem is an old number guessing game.
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The problem is an old number guessing game.
The computer picks a number from 1 to 100, and you have 7 tries to guess the number it picked.
Produce the pseudocode
Create an accurate flow chart using Visio
Copyright 2004, Richard T. Vannoy II

4. The Solution:
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One, organized way to approach this problem uses the acronym D.I.P.O.
D = Declare
I = Input
P = Process
O = Output
Copyright 2004, Richard T. Vannoy II

5. D.I.P.O. D = Declare (the variables)
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D = Declare (the variables)
The First Step
What numbers will need to be stored?
What names will need to be stored?
What other data needs to be stored?
Anything used or manipulated by the computer must first be stored in memory.
Copyright 2004, Richard T. Vannoy II

6. D = Declare
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For the number guessing game we will need someplace to store…
the number the computer picks.
(We’ll call this variable number)
the number of guesses made by the human.
(We’ll call this variable howMany)
The number the human enters as a guess.
(And call this variable guess)
Copyright 2004, Richard T. Vannoy II

7. I = Input The input for this program is easy…
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The input for this program is easy…
The human’s guess is the only input
Copyright 2004, Richard T. Vannoy II

8. P = Process The process for this program is easy…
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The process for this program is easy…
Read the human’s guess from the console
Compare the guess to the computer’s number
Route to “Guess again” (with a hint) or “Game over” depending on human guess
Copyright 2004, Richard T. Vannoy II

9. O = Output
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During the guessing process, there will be four possible outputs:
“Your guess was too low!”
“Your guess was too high!”
“You Got IT!!!”, (You win!) and
“Too many guesses. (You lose.)”
…and at the end, the output:
“Play Again?”
Copyright 2004, Richard T. Vannoy II

10. The Chicken or the Egg? Which comes first?
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Which comes first?
The pseudocode? or
The flow chart?
Actually, it doesn’t matter….
Do one or the other first, or
Do them both, side-by-side, at the same time.
Copyright 2004, Richard T. Vannoy II

11. The Pseudocode
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Because of this PowerPoint format, it would be cumbersome to do both together, so I’ll make the choice most programmers would pick: pseudocode first.
At this point, it would be good to have all the previous slides printed out and available, so that you can better see all the requirements and components.
Copyright 2004, Richard T. Vannoy II

12. The Pseudocode
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The “Big Picture”, meaning lacking details or specifics of the pseudocode would look like this.
Computer picks a number
Human gets 7 guesses
Possible responses:
- Too high
- To low
- Correct! You win!
- Too many guesses. You lose.
Play again?
Copyright 2004, Richard T. Vannoy II

13. Modules/Subroutines
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Although this program is too small to normally warrant the use of several modules or subroutines, I will use them here just to help you keep in mind the idea that separate tasks should be in individual modules.
Copyright 2004, Richard T. Vannoy II

14. Modules Here is what the “big picture” flow chart looks like in Visio:
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Here is what the “big picture” flow chart looks like in Visio:
Copyright 2004, Richard T. Vannoy II

15. Modules
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Next, let’s try to write some pseudocode to match each of these shapes.
(Look at the previous slides and apply what you know here.)
Copyright 2004, Richard T. Vannoy II

16. Modules Initialize: (We need to store) integer number (1-100)
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Initialize: (We need to store)
integer number (1-100)
integer guess (1-100)
integer howMany (1-7)
Copyright 2004, Richard T. Vannoy II

17. Modules Process: (Do this up to 7 times) Get human guess
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Process: (Do this up to 7 times)
Get human guess
Compare guess with number
Output message:
Too high! (Repeat guess)
Too low! (Repeat guess)
You win! (Exit to Play Again)
You lose. (Exit to Play Again)
Copyright 2004, Richard T. Vannoy II

18. Modules Play Again: If YES, return to start If NO, end program
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Play Again:
If YES, return to start
If NO, end program
Copyright 2004, Richard T. Vannoy II

19. Complete Pseudocode Initialize: (We need to store)
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Initialize: (We need to store)
integer number (1-100)
integer guess (1-100)
integer howMany (1-7)
Process: (Do 7 times)
Get human guess; Compare with number
Based on Guess, Output message:
Too high! (Repeat guess)
Too low! (Repeat guess)
You win! (Exit)
You lose (Exit)
Play Again:
If YES, return to start
If NO, end program
Copyright 2004, Richard T. Vannoy II

20. What’s Next?
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So… We have the big picture and the major items of both the pseudocode and the flow chart
Now we need to go into more detail.
This is called “Top Down” design
Copyright 2004, Richard T. Vannoy II

21. Top Down?
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Top Down means to start with the big picture, then step by step, provide more info and break down the tasks to smaller and smaller units.
The theory is that gradually, you will have a detailed, complete set of steps to perform the task.
Let’s continue our breakdown…
Copyright 2004, Richard T. Vannoy II

22. Initialize()
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From the previous slides, what needs to be declared here as places to store something?
Copyright 2004, Richard T. Vannoy II

23. 3/28/2017
Copyright 2004, Richard T. Vannoy II

24. 3/28/2017
In case the game is played again, we need to set the number of guesses to zero.
Copyright 2004, Richard T. Vannoy II

25. 3/28/2017
This is the complete flow chart for process(), but let’s start over and build each part of the chart with an explanation
Copyright 2004, Richard T. Vannoy II

26. 3/28/2017
First, we must have an input from the human, their guess. (We could verify this to be a number from 1 to 100 if desired.)
Copyright 2004, Richard T. Vannoy II

27. Next, we must ask several questions.
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Next, we must ask several questions.
If the human’s guess is less than the computer’s number, we print a hint that the guess is too low.
Copyright 2004, Richard T. Vannoy II

28. 3/28/2017
We’ll come back to “Too low” shortly, but let’s ask the next question: Is the human’s guess bigger than the computer’s number?
Copyright 2004, Richard T. Vannoy II

29. 3/28/2017
We’ll come back to “Too low” shortly, but let’s ask the next question: Is the human’s guess bigger than the computer’s number?
Notice that we put “Yes” and “No” at the two outputs of the decision diamond to show the flow direction for each answer.
Copyright 2004, Richard T. Vannoy II

30. If the guess was too high, we show the “Too high” hint.
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If the guess was too high, we show the “Too high” hint.
Copyright 2004, Richard T. Vannoy II

31. 3/28/2017
If the answer to both of these questions was “No”, what is the only possibility left?
Copyright 2004, Richard T. Vannoy II

32. 3/28/2017
If the guess was not too high, AND not too low, then the human guessed the computer’s number.
Display the good news.
Copyright 2004, Richard T. Vannoy II

33. So the game is over. Let’s exit.
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So the game is over. Let’s exit.
(Which takes us to the “Play Again?” section of the code.
Copyright 2004, Richard T. Vannoy II

34. 3/28/2017
Now we need to go back and add the steps required after the “Too low” and “Too high” messages are displayed.
Copyright 2004, Richard T. Vannoy II

35. 3/28/2017
In either case, the human made the wrong guess, so add one to the number of guesses taken.
Copyright 2004, Richard T. Vannoy II

36. 3/28/2017
Did the human take too many guesses without getting the correct number?
Copyright 2004, Richard T. Vannoy II

37. 3/28/2017
If the human took too many guesses, time to exit and go to “Play Again?”
Copyright 2004, Richard T. Vannoy II

38. 3/28/2017
And finally, if the human has any guesses left, send them back to guess again.
Copyright 2004, Richard T. Vannoy II

39. Now, You Finish Up the Chart
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And lastly, the “Play Again?” section needs to ask the question:
Do you want to play again?
(Input the human’s answer.)
If the answer is “Yes” direct the flowchart back to the beginning of the program.
If the answer is “No” direct the flowchart to “End”.
You make the flowchart for this part.
Copyright 2004, Richard T. Vannoy II

40. 3/28/2017
Copyright 2004, Richard T. Vannoy II