Class 13: Random Fun

Held Friday, September 20, 2002

Summary

Today we explore some fun applications of the random procedure in the context of CGI scripts. We will spend some of today's class on a different learning technique: group design of a Web service.

Assignments

• Read Repetition with Recursion.

Notes:

• Welcome to any visiting parents.
• The problem with Web pages appearing in an Courier was due to an error in my sample HTML. Where we use <lang="eng">, we should be using <lang="en">.
• Are there any questions on homework 3?
• Warning: Last Friday's class was Friday the 13th. This Friday's class is Class #13.

Overview

• Designing a dice game
• Lab: Randomness and Simulation

Review: The random Procedure

• The (random n) procedure generates an unpredictable number between 0 and n-1.
• You can use that result as you'd use any other number.
• You can add to it.
• You can use it to select between elements in a list.
• To roll a die

  (+ 1 (random 6))
  

• To pick a random word

  (list-ref (list word0 word1 word2)
            (random 3))
  

A Dice Game

• We'll begin class by thinking about the design of a Web-based dice game.
• The player has an account of some amount of money.
• Each round, the computer rolls two dice.
• If the sum is even, the computer wins.
• If the sum is odd, the player wins.

Key Questions

• How do we roll two dice?
• How do we keep track of the amount the player currently has?
• How do we start the game?
• What goes on each Web page?

Lab

• We'll explore this game in the lab.