1. Lesson Objectives Aims You should be able to:
Identify the components of a problem
Identify the components of a solution to a problem
Determine the order of the steps needed to solve a problem
Identify the sub-procedures necessary to solve a problem

2. Note
Before we start:
This lesson makes use of a task described in the “learn VB” course. You can get a LOT of extra help/hints in that document if you’ve not already read it.

3. Procedure
Procedure:
A block of code which performs a specific task or sub task
It may allow data to be sent in and may give data out again when complete (passing variables)
It is re-usable
It can be called from anywhere in your code

4. Thinking procedurally
Thinking procedurally is simply the ability to:
Break a problem down into chunks
Decide which could be a re-usable block of code
Work out what inputs the procedure will need to do the task
Work out what outputs the procedure should produce
Make those procedures

5. Task
The only way to learn this is practise, applying it to programming tasks.
You are going to make a program which simulates a really simple slot machine type game. It will do the following things:
Give the user £1 starting money and take 20p off per go
Spin the reels
Display the result of the spin – win or loss depending on some simple rules
Allow the user to select if they want another go or to take their winnings.

6. Method
Decompose the problem – what are the main tasks this program should perform
Abstract – Make sure you are only focussing on what is strictly necessary to complete the task
Decide what variables your program will need
Algorithms – what will your code need to calculate/manipulate/produce
Outline algorithm – what will the basic structure of your code be?
Decide what procedures you should produce.

7. Have a go, then I’ll walk you through my thinking.

8. As I see it the program will need to:
Decompose/Abstract
As I see it the program will need to:
Spin the reels
Compare the reels to check the outcome
Calculate profit/loss
It will need to do all of these things whilst the player has enough money to play again (or quits)

9. Variables
If we read the task, we obviously need to store the following information:
Money
Reel 1 value
Reel 2 value
Reel 3 value

10. Algorithms
Loop while money is > 0 and user wants to play again Reduce money by 20p Do spin Show outcome of spin Update money based on outcome Exit loop if no money left Ask user if they want to proceed Exit loop if they don’t want to End loop

11. Procedures
Clearly the following things happen repeatedly:
Spinning the reels
Calculating the outcome of the spin
Updating the money the user has

12. Code outline
This would lead us to this initial structure in VB:

13. Next steps…
The outline algorithm goes in the MAIN() sub and controls our program – it should be trivial to convert to code
Final step – outline what each sub will do.

14. Main() Create the game variables Loop round, allowing the user to play until no more money or no more turns required Call DoSpin() Call CompareReels() Display outcomes Call UpdateMoney() Ask if the player wants another turn. DoSpin() – Inputs (none), Outputs (reel values) Generate three random numbers – one for each reel Return these numbers CompareReels() – inputs (reel values), outputs (winnings/losses) Compare the three random numbers to the rules: Return any winnings or losses this combination will cause UpdateMoney() – inputs (player money, winnings/losses), outputs (updated player money) Reduce the player’s available money by 0.2 Increase or decrease the player’s money according to any winnings they may have earned or losses they have made Display the players current balance

15. Next step
Code it!

16. Review/Success Criteria
You should know:
The