CS U216 -- Algorithms and Data Structures for Engineers

Assignment 5

Due 9 June, 2005

Assignment 5 involves making changes to the music classes that were discussed in lab. (The source code for these classes is in the file music.h, available at http://www.development.ccs.neu.edu/home/peterd/csu215/LabExamples.aspx). The file you submit should be a header file, such as a modified version of music.h. The submitted file should include compiler directives to protect against multiple inclusions. These compiler directives are already in music.h. The submitted file should not include the function main().

• Due to my musical ignorance, I did not realize that the term used in music for a set of pitches which are separated by octaves, for example all of the "C"s, is a "pitch class". In lab, I called these scale positions, and created a ScalePosition class. For this assignment, you should rename the ScalePosition class to be the PitchClass class. If you just change the name of the class, you will get an error when you attempt to build the classes in music.h. Add a comment to your file that lists all of the places you needed to change for your classes to build and run correctly.
  
  
• Add a new constructor to the PitchClass class, which takes a string as an argument. The following strings should result in the creation of "valid" PitchClass objects:
  • A string consisting of a single upper case letter A through G
  • A string consisting of a single upper case letter A through G followed by a '#' symbol (for example "C#").
  • A string consisting of a single upper case letter A through G followed by a lower case 'b' (for example "Bb").
  The following table gives numeric encoding that should be used for PitchClass objects that are created with a single letter.

  A	0
  B	2
  C	3
  D	5
  E	7
  F	8
  G	10

  
  If the argument to the constructor is a string ending in '#', the numeric encoding of the created object should be 1 greater than the encoding of an object created with a string without the '#'. For example, "C#" should create an object with the encoding 4, because "C" creates an object with the encoding 3.
  
  If the argument to the constructor is a string ending in 'b', the numeric encoding of the created object should be 1 less than the encoding of the corresponding object created without the 'b', except that "Ab" should be encoded as 11, not as -1.
  
• Modify the constructor(s) for the Note class, so that only Note objects created with positive durations are valid. (Only for those notes will the isValid() method return true).
• Create a Rest class, which is similar to the Note class, but has only a duration, and no pitch. The Rest class should have a play() method, which at this point does nothing.
• Create a Voice class. The Voice class should have a play() method, which at this point does nothing. The Voice class should have an addNote(Note n) method. Calls to the addNote(Note n) method should somehow store the arguments to those calls "within" the object. There are many ways to do this, and I'm sure we will cover some in class. One possible implementation, which is very simple, but may not be the best is for your class to have private member fields
  • Note notes[SIZE];
  • int nextNoteToRecord;
  When a Voice constructor is called (also known as "invoked"), nextNoteToRecord should be initialized to 0. Then each call to addNote(Note n) should record its argument in notes[nextNoteToRecord] if nextNoteToRecord is less than SIZE. Following that, nextNoteToRecord should be incremented,

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Last updated 2 June 2005.