COP 1220 (C Programming) Project #3

Purpose:

To practice C statements and programming ideas, such as loops, arrays, and structures.  To practice good programming techniques, style, design, testing, and good program documentation, on a medium-sized programming example in the database and artificial intelligence domains.

Background:

(The idea for this assignment, and the story and clues given below, was adapted from the book Great Ideas in Computer Science: A Gentle Introduction, by Alan W. Biermann.  ©1990 by Massachusetts Institute of Technology, published by The MIT Press, Cambridge, Mass.  Pages 109 and 144.  Used with the kind permission of the publisher.)

As the afternoon sun faded on the village green, Chief Inspector Lestrade of Scotland Yard was just lighting his evening pipe when the jangling of his phone interrupted his mellow mood.  The call was from a terrified Miss Secrest, who moments before had found Lord Peter Dunsmore collapsed on the drawing room floor of Dunsmore Manor.  He was dead.  The Lady Emily, Lord Dunsmore's wife, had collapsed from the shock and had been taken to her chambers where the family doctor ministered to her.  Miss Secrest begged the Inspector to hurry over to Dunsmore Manor.  This he did, after phoning the Medical Examiner and noting the time was a few minutes after 5:00 P.M.

After examining the body, the M.E. pronounced the cause of death as a lethal dose of poison administered within the last few hours.

After questioning the family, servants, and visitors Inspector Lestrade had many facts but was having trouble putting them together.  So naturally he turns to you for help, a world-renown computer expert.  You decide to build a database of the facts which will allow the Inspector to find related facts.  For example, if the Inspector asks "Who visited the manor today?" your program might respond:

	Mr. Mason visited at 3:00 P.M.
	The professor visited at 3:00 P.M.
	Miss Secrest visited at 5:00 P.M.

or if the query is "Tell me about Mr. Mason?" your program might respond:

	Mr. Mason has hobby tennis
	Mr. Mason visited at 3:00 P.M.
	Mr. Mason is a chemist

(Naturally, the queries will not be in English, but in your query language.)

After entering all known facts and using your system for awhile, Inspector Lestrade was able to identify a prime suspect, the only person who had an apparent motive, access to the poison, and a way of administering it to the victim.  After confronting his suspect with the relevant facts, the suspect broke down and confessed.  Thanks to you and your computer skills, Justice has triumphed once again!

Programming Requirements:

You must write a stripped-down database application capable of storing facts.  A fact in this program has three parts or fields: a subject (a noun phrase), a relation (a verb phrase), and an object (a noun phrase).  For example:

• You must store the facts as an array of structs, where each struct has three fields.  Each field is a string of at most 50 characters.  Your system must be able to hold at least 100 facts.
• Your program should have a simple menu based user interface.  (Use only Standard C for this!  Do NOT use Borland extensions to move the cursor or clear the screen.  You will NOT get full credit if I can't run your program on DOS, UNIX, or Macintosh systems!  In short, write a portable program.)
• There should be a menu choice to Add a fact to the database, to Query the database (that is, ask questions and have the system print out the matching facts), to print some Help, and to eXit the program.
• To add a fact, you program should prompt the user for a subject, a relation, and an object.  If the data is OK, add the fact to your table.  The amount of error checking done is up to you, but make sure each field has at least one character and at most 50 characters.
• To display help, you should print out information on facts, including the number and size of each field, and the maximum number of facts that can be entered into the database.  The user also needs to know how queries work, and how any other additions and extensions work.
• To make a query, the program should prompt the user for a subject, a relation, and an object.  This is called the template fact.  It should then check each and every fact in the table to see if it matches the template.  All matching facts from the table should be printed.  At a minimum, your program should print any facts that are an exact match, field by field, with the template fact.
  You must allow a "don't care" symbol for any or all field(s) of the template fact.  This symbol is called the wild-card character.  Use a question-mark as the wild-card character.  For example, if the template fact has subject = "Lord Dunsmore", relation = "?", and object = "?", then all facts in the table with a subject of "Lord Dunsmore" should be printed.
• If you have the time and inclination, you might extend your program with any or all of the following:
  • Allow case insensitive matching.  (Case insensitive means a field containing "Lord Dunsmore" would match the corresponding template field of "lord dunsmore".)
  • Allow partial field matching.  (Partial field means a field containing "Lord Dunsmore" would match the corresponding template field of "Duns".
  • Add checks when adding facts to make sure the wild-card character isn't entered, and that the table isn't already full.
  • Add another menu choice "Delete" which will prompt for a template fact (just like Query does), and delete all matching facts from the table.  (This can be done most easily by marking one of the fields of each deleted fact and leaving it in the table.  When matching facts for a query (or even a future delete) operation, you simply skip over any marked facts.
  • Add a menu choice to save the database of facts in a file.  The facts can be saved as one fact per line, with the wild-card character to separate the three fields (since you know the wild-card character won't appear in any field).
  • Allow initializing the table from a previously created file of facts whose name is provided as a command line argument.  (See the previous paragraph for a possible file format.)
• A sample output is attached.  Your output should look something like this when run using the test data provided.  Note that your program may look very different than this ultra-fancy one; just make sure some sort of menu scheme is used.
• Copies of clue.exe and clue.dat (see below) can be downloaded from the instructor's website.  This version has many of the extra features mentioned above.

To be turned in:

You can (and should!) test your program with several different sets of facts (databases).  However, a printout of the following must be turned in:

• Starting up your program (showing your user interface);
• Adding 2-5 facts (of the thirty-odd facts listed below and stored on-line as mentioned above);
• Performing 3-10 queries (showing whatever features you have added, but at a minimum one query that matches without a wild-card, one query which matches using a wild-card in one (or more) fields, and one query which doesn't match any facts;
• Display help;
• Show off any other extra features of your program;
• As usual, in addition to this printout you must turn in a printout of your program, and also a floppy disk with your program as the only .C file on the disk.  (You can have other files on it such as a .DAT file or a .EXE file.)

Extra-Credit of 1 point will be awarded if you can identify the murder!  Write the name on the bottom of the printout of the output.

Sample abbreviated output (With user input shown in boldface):

(command line:  C:\> clue clue.dat)

        [Loaded 31 facts from file "Clue.dat".]



                        C L U E   D A T A B A S E
                        -------   ---------------



                (A)  Add a fact to the database

                (D)  Delete a fact from the database

                (Q)  Query the database

                (S)  Save the database in a file

                (H)  Print additional Help

                (X)  eXit Clue



        Enter a choice from the menu above: h

A fact has a subject, a relation, and an object.
Each field is limited to 50 characters.
...
Type Return (Enter) to continue...
<MENU IS REPRINTED HERE>
        Enter a choice from the menu above: q
        For each field enter the text to match, or the wild-card
        symbol ("?") to match any text in that field.


        Enter the subject: dunsmore
        Enter the relation: ?
        Enter the object: ?


                THE MATCHING FACTS:

        Lord Dunsmore is married to Lady Emily
        Lord Dunsmore has hobby tennis
        Lord Dunsmore has rival Lord Secrest
        Lord Dunsmore died of poison

        Another query? (Y/n) 


        Enter the subject: Professor Plum
        Enter the relation: stabbed with the knife
        Enter the object: ?


        No matching facts found!
        Another query? (Y/n) 


        Enter the subject: ?
        Enter the relation: visit
        Enter the object: ?


                THE MATCHING FACTS:

        Mr. Mason visited at 3:00 P.M.
        The professor visited at 3:00 P.M.
        Miss Secrest visited at 5:00 P.M.

        Another query? (Y/n) n

Type Return (Enter) to continue...
<MENU IS REPRINTED HERE>
        Enter a choice from the menu above: a
        For each field enter the exact text to match.



        Enter the subject: ?
        Enter the relation: visited
        Enter the object: ?

        ***Warning!  A Field must NOT contain the wild-card character "?"!

        Add another fact? (Y/n) y


        Enter the subject: This
        Enter the relation: is
        Enter the object: fun!

        Add another fact? (Y/n) n

Type Return (Enter) to continue...
<MENU IS REPRINTED HERE>
        Enter a choice from the menu above: d
        For each field enter the exact text to match, or the wild-card
        symbol ("?") to match any text in that field.



        Enter the subject: ?
        Enter the relation: ?
        Enter the object: fun


                DELETING THESE FACTS:

        This is fun!

Type Return (Enter) to continue...
<MENU IS REPRINTED HERE>
        Enter a choice from the menu above: x
Really Quit? (Y/n) y
Do you want to save the database to disk before quitting? (Y/n/c) n
C:\>

Test Data:

(The file clue.dat contains the data shown below):

Lord Dunsmore?is married to?Lady Emily
Miss Secrest?called?the Inspector
The gardener?is married to?the maid
Poison?can be procured by?a blood relative
Mr. Mason?visited?at 3:00 P.M.
A shared hobby?causes?friendship
The gardner?was fired by?Lord Dunsmore
Lord Dunsmore?has hobby?tennis
The maid?set tea?at 2:45 P.M.
The gardener?has hobby?music
Lord Secrest?has hobby?philosophy
Lord Dunsmore?has rival?Lord Secrest
Mr. Mason?is?a chemist
The Inspector?is a customer of?Mr. Mason
Lord Secrest?has daughter?Miss Secrest
The buttler?owes money to?Lord Dunsmore
The buttler?served lunch?at 12:00 P.M.
The professor?has hobby?philosophy
The professor?visited?at 3:00 P.M.
Lord Secrest?is a customer of?Mr. Mason
The professor?gives gifts to?Lady Emily
Tea?is served?at 3:00 P.M.
Miss Secrest?visited?at 5:00 P.M.
Poison?is procured from?a chemist
Lord Dunsmore?died of?poison
Lady Emily?has hobby?music
Poison?can be procured for?a friend
Mr. Mason?has hobby?philosophy
Poison?kills?within one hour
The professor?was once a suitor of?Lady Emily
Miss Secrest?discovered the dead body of?Lord Dunsmore