CMSC 201
Programming Project Two Solution

General Comments

• Expected levels of documentation.
  1. Pay attention to the naming for #defines and variables
  2. Note the comment style -- the format of comments, when and where comments are provided.
  3. The file header comment

  Top-Down Design

  The purpose of this project was to practice top-down design and implement that design with functions. Any program that presents a list of choices almost always has a switch statement with a case for (almost) each choice, and a function that processes that choice. That's how this program is designed.

  As you read the project description the following tasks can be identified

  1. print a greeting to the user
  2. seed the random number genertor
  3. present the user with a menu
  4. process the menu selection until the user types 'Q' or 'q'

  The last item above can be further refined into

  1. if the user types 'H' or 'h', print the help menu
  2. if the user types 'G' or 'g', print the current game statistics
  3. if the user types 'Q' or 'q', print final stats and exit
  4. if the user type 'P', 'p', 'R', 'r', 'S', or 's', play the game

  The last item above can be further refined into

  1. generate a choice for the system
  2. decide if player wins, losses or ties
  3. update appropriate count of wins, losses or ties

  You may have refined your tasks differently, or to a greater extent than I did.

  As a result of my top-down design, I identified these functions

  1. void PrintGreeting (void) -- displays the greeting on the screen
  2. void GetSeed ( void ) -- gets random number seed from user and calls srand()
  3. void PrintHelp ( void ) -- prints the help menu
  4. int GetPlayerSelection ( void ) -- input the user's menu selection as a single char and translates it to an integer
  5. int GetSystemSelection ( void ) -- chooses Rock, Paper or Scissors for the "system"
  6. int CompareChoices ( int playerChoice, int systemChoice ) -- compares the user's and system's choice and returns the result (player wins, player loses, or tie)
  7. void ReportOutcome ( int result ) -- displays the result of the last comparison to the user
  8. void PrintGameStatus ( int wins, int loses, int ties ) -- displays the number of wins, losses and ties to the user
  9. void PrintFinalStatus ( int wins, int loses, int ties ) -- displays good-bye message and final game statistics to the user

  Notes

  There a few interesting techniques in the code that are worth mentioning. If you have any questions about the code, feel free to ask.
  • This code doesn't use the "priming read" technique, even though a 'while' loop is used. Instead the variable that is the user's input and controls the while loop is initialized to INVALID (it could be anything that's not QUIT) so that the execution will enter the while loop the first time. This is often easier than the "priming read"
  • I translated the single character input into an int because integers seem easier to work with than chars.
  • Should there be a function like GetSystemChoice() which is just one line of code? I chose to do so because
    1. a meaningful function name helps make the code easier to read and understand
    2. Someday the method for generating the system choice may be much more complex and not be just on line of code
    3. Someday we may want to generate the system choice in more than one place.
    Note that 2 of these reasons have to do with possible future changes to the code -- that's maintainability.
  • The function ReportOutcome() has a default case in its switch statement which should never be executed (other functions could have done the same). This is done as defensive mechanism against myself. During the development of my program, a coding error may have caused the default case to be executed, alerting me to my error.
  • Note how some functions (like PrintFinalStatus) use other functions to keep from duplicating code.
  • Note the obvious use of #defines for the menu choices.