In this lab, you'll investigate how vectors work and you'll use another animation. Before coming to lab you should read/review chapter 8 on vectors in Astrachan/Tapestry. The lab uses vectors to implement an automatic scoring program for a bowling alley.

In the last lab we were introduced to the basic concept of having an object that did something (take a random walk), and had another object (an observer) that reported something about the random walk. We used samba to show the current location of the walker using animation. In this lab, we will have multiple observers. The first class (the Lane) is your bowling alley. The ball will roll down the lane and hit some pins, etc. The second class (the Scorer) will mark down your score on the score sheet.

Lab 3 table of contents

General rules of Bowling

If the first ball rolled knocks over all 10 pins, then only one ball is rolled in the frame, this is called a strike. If the first two balls are used to knock down all 10 pins this is called a spare. A mark is a frame in which either a strike or a spare is rolled. Marks are good because they increase your score. You don't need to know how to score bowling because the automatic scorer takes care of this for you!

In the 10th and last frame, if you knock down all 10 pins you get 3 rolls instead of 2. This can increase your score.

If you fail to knock down any pins, you haven't rolled very well. If your ball lands in a special part of the alley called a gutter, then you've rolled a gutter ball. Not all zeros are gutter balls, but all gutter balls are zeros.

back to lab contents

Compiling and Executing/Using the Animator Samba

In this section of the lab you'll copy files, compile a basic simulation of a bowling alley, and view the simulation using samba again.

First change into your cps100e subdirectory (type pwd to verify where you are). Create a lab3 subdirectory by typing mkdir lab3 and change into this subdirectory (be sure to check that you're in the lab3 subdirectory.) Now copy the files for the lab (don't forget the . when copying).

You should see the files listed below (these are links to the files in case you use Netscape, and for users outside of Duke).

• Makefile
• main.cc
• bowler.h
• bowler.cc
• game.h
• frame.cc
• game.h
• game.cc
• observer.h
• scorer.h
• scorer.cc
• lane.h
• lane.cc

Be sure you're in the lab3 subdirectory, and check to see that all files are there (type ls). Then, from an xterm window (at the prompt [1] ola@teer8% or similar) compile the first version of the program by typing: make bowl . This should compile several files and link them together with the library libtapestry.a. Now run the program by typing: bowl at the prompt. Although the program may seem to do nothing, it is creating a file to store information about a game of bowling that was simulated. If you type ls after the program runs, you should see a file called bowl.out which was created by bowl. If you type ls -lt you'll see files sorted by time of creation, so bowl.out should be first.

Bowling

( If you get a message samba: command not found, then you didn't change your path in lab1 and you should check with a TA. )

To make samba work, you'll need to click on the start button in the Polka Control Panel. You can slow the animation down using the slide-bar. Because there are two windows for this animation, you might want to move them around to make it easier to see both the ball/pins and the auto scorer. You can pause/start using the pause/start button. To quit samba, use the quit button.

back to lab contents

Modifications to Bowling: Adding Vectors

In this part of the lab you'll change the Bowling program so that you can input the number of bowlers, the names of each bowler, and the skill level of each bowler. The first bowling program scores a game for just one person.

More Bowlers

1. Run emacs, either by clicking on the emacs icon in the menubar (if there is one) or typing emacs & at a prompt.

2. Load (use the file menu or C-x C-f) the file main.cc.

3. Add a prompt in the PlayGame function which asks the user to input some number of players between 1 and 5. You should try to use prompt.h for this.

4. Change the definition of a single game (for the bowler "Owen") to a vector of games, one for each player. Change: Game game("Owen");

   to

   Vector<Games> players(numPlayers); This will create a vector of Game objects that will have a bowling match. Although the name of the class is Game, think of each element of the vector players as a player. You'll need to initialize each Game/Player by setting the game's name and skill-level, this is described below.

5. Add a loop (right after the Vector definition you just made) which asks the user for each player's name and sets each player's name. Hint: you will call the member function Game::SetName() inside the loop, using a syntax similar to players[k].SetName(...). Look at the file game.h to see what parameter(s) SetName takes.

6. In addition to setting each bowler's name, you should set each bowler's skill level. Use the member function Game::SetSkillLevel() to set the skill level of each player. You should prompt the user for the skill level of the bowler. 0 is a really bad bowler, 30+ is a professional bowler. The declaration for the function SetSkillLevelis in bowler.h

7. In the loop, in addition to setting names and skill-levels, you'll need to attach the observers lane and scorer to each player. To do this you'll use a statement like: players[k].AttachObserver(lane); and you'll need to attach the scorer as well.

8. Change the loop that calls game.TakeTurn() so that each player takes a turn. To do this you'll use the loop already written and shown below: for (k=0; k < Game::MAX_FRAME; k++) { } but you'll include a loop inside this loop so that every game/player in the Vector players takes a turn. You'll need a statement somthing like players[j].TakeTurn(), you'll need to think about this. The key is that the outer loop executes 10 times, once for each frame. The inner loop needs to execute once for each player, so that each player will take a turn.

When your program compiles and executes, be sure to run Samba on the output file to verify that all players are scored.

Adding Functions, Passing by Reference

For this part of lab, you'll add a new function MatchStats that computes statistics for the match of several players.

Since there are now several players instead of just one, you should first change the name PlayGame to PlayMatch. To do this

• Make sure that main.cc is the active buffer in your emacs session. Type M-x replace-string, that's Escape-x, followed (in the minibuffer) by "replace-string". You can hit the TAB key after "repl" and the command will be completed (partially). If you hit TAB again, the choices will appear and you can type "st" TAB to complete the command, then hit return.

• At the prompt Replace string: type "PlayGame" and press return.

• At the prompt Replace string PlayGame with: type "PlayMatch" and press return. This should replace all occurrences of PlayGame with PlayMatch. Emacs supports several commands to search and replace, both from the Edit-menu, and with keyboard shortcuts.

You'll now add a function MatchStats. Pass the vector of players from PlayMatch to MatchStats. You should pass the vector as a const reference parameter. The number of elements in the vector is accessible as players.length() since the vector was defined to hold exactly as many players as are in the match.

In the function MatchStats you should use the vector and appropriate member functions to print the following statistics; these should be printed using cout << ...; the output will appear on the screen and you'll be able to run Samba on bowl.out to verify if your stats are correct.

• Print the name and final score of each player. Names are accessible using Game::GetName() and the final score is accessible using Game::TallyScore where you'll need to pass 10 (or Game::MAX_FRAME) to get the complete score. These member functions are described in game.h.

• Compute the number of marks each player has, and the number of strikes. See rules of bowling above for the definition of a mark.
  • To compute marks for a player you'll need to get each frame in the player's game. The function Game::GetFrame() returns a frame, so you can use the function (defined in game.h) to retrieve each frame and store the frame in a local variable, e.g., Frame f = ....

  • You'll then need to use the Frame member function Frame::GetScore() (defined in frame.h) to get the score for the frame. If the score is greater than or equal to 10, it's a mark. If the score on the first ball is a 10 it's a strike.

  • To find the score on the first ball you'll need to use the frame member function Frame::GetPinCount() which returns the number of pins knocked down with ball number 0, 1, or 2 (remember that there can be up to three balls per frame). The GetPinCount function is defined in frame.h.

Submitting The Lab

    submit100e lab3.N README main.cc 

You can enter the files in any order (you don't need to submit observer.h, frame.h, frame.cc, scorer.h, scorer.cc, lane.h, or lane.cc because they didn't change, (but you can submit them.)

Remember that every assignment must have a README file submitted with it (please use all capital letters). Include your name, the date, and an estimate of how long you worked on the assignment in the README file. You must also include a list of names of all those people with whom you collaborated on the assignment.

You also must turn in the inlab questions either by turning in the sheet during lab or by submitting the answers with your README.

back to lab contents

Extra Credit

    submit100e lab3.N.xtra README main.cc