In Class: Week 6, Tuesday

Run update21 to create a week06 subdirectory and copy example programs to your cs21/class directory. From there, move to your week06 directory:

    $ update21
    $ cd 
    $ cd cs21/class/week06
    $ pwd
      /home/your_user_name/cs21/class/week06
    $ ls
      fivequestions.py  grades.py  squareevens.py  syracuse.py
	

Using functions with objects

1. First, we will open up drawshapes.py from last week (week05 directory) and use functions to simplify the repetitive process of getting user mouse clicks. On your own, write another function (drawTriangle) that further simplifies the task of creating a triangle multiple times.

   Practice with functions with mutable object parameters:

2. In squareevens.py, we examine the effect of handing a mutable object off to a function. Specifically, we will implement a function that takes in a list of numbers and squares all of the even values. Next, trace through the code to see how modifying mutable data types affects the original argument in the main() function.

   Error checking user input

3. Open up grades.py. This is the solution to the first problem in lab 3. In the lab, we assumed the user gave valid input (i.e., a number between 0 and 100). I have added error checking to the solution by outputting an error message to the screen if the user does not provide a valid number. Once you are familiar with while loops, modify this code to ask the user to reenter the score until they provide a valid number.

   Practice with while loops

4. open syracuse.py in vim. We will implement a function syracuse, that takes a starting value and computes the Syracuse sequence for the value (printing out each term that is computed).

   To kill a program with an infinite loop, hold down the CNTRL and the c keys (CNTL-C).