Lab 4: Conditionals and While Loops

Goals

After the lab, you should be proficient at

  1. solving advanced problems using for loops and conditionals
  2. using the exit function available in the sys module
  3. solving indefinite loop problems

Linux

  1. As usual, create a directory for the programs and output you develop in this lab.

Objective: Programming in Python

We'll practice writing several Python programs, each in their own text file. Name the files lab4.1.py through lab4.7.py.

Your programs will be graded on correctness, efficiency, style, and how well you tested them. Make sure you adhere to the good development and testing practices we discussed in class. Your code should be readable and your output should be useful and well-formatted.

After you've developed a correct solution to each program, close reopen the IDLE "shell" by running the program again (using F5), demonstrate that the program works using several good test cases, and save the output to a file named lab4.x.out, where x is the problem number.

  1. (20) Write a program that displays the multiplication tables from 0 to 12. Start small (maybe multiplying 2 to 4) and add formatting last.

    Example output:

     x |   0 |   1 |   2 |   3 |   4 |    5 |   6 |   7 |   8 |   9 |  10 |  11 |  12 |
    -----------------------------------------------------------------------------------
     0 |   0 |   0 |   0 |   0 |   0 |    0 |   0 |   0 |   0 |   0 |   0 |   0 |   0 |
     1 |   0 |   1 |   2 |   3 |   4 |    5 |   6 |   7 |   8 |   9 |  10 |  11 |  12 |
     2 |   0 |   2 |   4 |   6 |   8 |   10 |  12 |  14 |  16 |  18 |  20 |  22 |  24 |
    ...
    12 |   0 |  12 |  24 |  36 |  48 |   60 |  72 |  84 |  96 | 108 | 120 | 132 | 144 |
    
  2. (15) The body mass index (BMI) is calculated as a person's weight in pounds times 720, divided by the square of the person's height in inches. A BMI in the 19-25 range is considered healthy. Write a program that calculates the BMI and prints a message telling whether they are above, within, or below the healthy range. If the user enters an unreasonable weight or height, print an error message and exit the program.
  3. (10) Write a program with a while loop that stops when the user enters a number that is evenly divisible by 6 (that is, there is no remainder). Print helpful output to the user.
  4. (35) Simulate a simple Craps game (without betting). Break the game into manageable pieces and build up. For example, make your program simulate rolling two dice and then test your program. Then, handle that the person rolls a 2, 3, 7, 11, or 12. Then, handle the point.

    The Rules

    1. A player rolls two dice. (How can you simulate rolling two dice?)
    2. There are three possibilities:
      • 7 or 11 wins. If the total of the dice is 7 or 11 then the player wins.
      • 2, 3, or 12 loses. If the total of the first roll is 2, 3, or 12 then the player loses.
      • Others become the point. If the total is any other number (4, 5, 6, 8, 9, 10) then this number becomes the point.

        The player keeps rolling until one of two things happen. Either the player makes the point and wins, or the player rolls a 7 and loses (craps out). Any number other than the point or 7 is of no consequence.

    After the first roll, print a message that tells the player that they either won, lost, or which "point" they have to play for.

    Example runs:

    *** This program simulates Craps (without the betting) ***
    
    You rolled a 11
    Congratulations!  You win!
    
    *** This program simulates Craps (without the betting) ***
    
    You rolled a 6
    The POINT is 6
    Roll again!
    
    You rolled 4
    Roll again!
    
    You rolled 6
    Congratulations!  You win!
    
    *** This program simulates Craps (without the betting) ***
    
    You rolled a 10
    The POINT is 10
    Roll again!
    
    You rolled 4
    Roll again!
    
    You rolled 9
    Roll again!
    
    You rolled 7
    Sorry!  You crapped out.  Luckily, money wasn't involved.
    

Extra Credit: Rainbow Dice (8 pts)

Simulate a game of Rainbow Dice, a Sprenkle family tradition. Note that Rainbow Dice is much simpler to implement than the Craps game. Demonstrate your program with a goal of 3, so that you don't print out too much output.

Finishing up: What to turn in for this lab

  1. IDLE and jEdit may create backup files with the "~" extension. Delete these files from your lab directory to save paper when you print.
  2. Copy your lab4 directory into your turnin directory.
  3. Create the document to print, using the printLab.sh command.
  4. View the file you just created using the gv command to ensure that you don't have any "junk" in the output.

    Again, you should probably print from the labs directory.

    Print the file using the lpr command introduced in the first lab.

Labs are due at the beginning of Friday's class. You should hand in the printed copy at the beginning of class, and the electronic version should be in the turnin directory before 1:20 p.m. on Friday.

Grading (80 pts)