knerr cs21 notes...

back to schedule

WEEK07: File I/O, top-down design
 F: more top-down design

 - Lab 7 due Tuesday Nov 3
 - quiz 3 file: /home/jk/inclass/
    (make sure you understand the quizzes!)
 - /home/jk/inclass/ is my wordcount solution from last class


 - let's try writing another program, using top-down design:

$ python 

 1. Rock
 2. Paper
 3. Scissors

your choice: 2

You chose Paper
*I* chose Paper

It's a T I E

$ python 

 1. Rock
 2. Paper
 3. Scissors

your choice: 1

You chose Rock
*I* chose Paper


 - what high-level steps need to be done to play the 
   rock-paper-scissors game?

      print the menu (1. rock, 2. paper, etc)
      get the user's choice
      make my choice
      determine the winner

 - the first step seems easy...write a function to print
   out the above menu of choices

 - the second step *can* be a one-liner, using input to
   get an integer. Or, to be more robust, we could write
   a getChoice function to get the user's choice and check
   it to make sure it's valid. I would probably start with
   the one-liner, just to see if things work, then later
   add the getChoice function

 - what kind of input do we want from the user? if they
   want to choose Rock, should they enter a 1, or the word
   "rock"?? This is a design choice you must make, and it
   will determine how the rest of your code works

 - the "make my choice" step can be done with randrange.
   how do we randomly choose between 3 options?

 - the "determine winner" step is a little harder. If the
   user's choice and the computer's choice are integers from
   1 to 3, how can we decide who wins? For example, suppose
   the user chose 1 (rock) and the computer chose 2 (paper),
   how do we figure out that the computer wins this game??

   Hint: can you write out all possible outcomes, and come up
   with an algorithm that determines the winner, based on the
   user's choice and the computer's choice?


 - write out
 - make the "get user's choice" section robust!
 - take a look at how can you read in x y data 
   from a file?