CSCI 151 - Program 2

B + - Trees

Dr. Melody Stapleton, Instructor

Due Date: self-paced Internet course - student determines due date

Your TA will provide the final input file(s) to run your program against.

Your are to implement an order 3 and an order 7 B+-Tree, as discussed in class and in Drozdek's book   The insert and delete processes for B-Trees needs to be modified to accommodate the special features of B+ Trees.

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You are to structure your main program to accept and interpret file input with the following format:

You will need to write your program to accept a series of "commands" from an input file. Listed below are the possibilities for the different categories of commands that will follow the above line in the input file(s):

• A     Integer_Key             To "add or insert" the integer into the B+-Tree.  Give an appropriate message for successful insertion, return a pointer to the bucket in which the node was inserted and print out the contents of the bucket that contains the newly inserted value.  Give an error message if the value is already in the tree.
• D     Integer_Key            To "delete" the integer from its B+-Tree node.  Give an appropriate message for successful deletion, return a pointer to the bucket in which the node existed prior to deletion, and print out the contents of that bucket prior to the deletion.  Give an error message if the value was not in the tree to begin with.
• S      Integer_Key            To "search" for the integer key.  For a successful search a pointer to the bucket that contains that contains the key will be returned.  Also, print out the contents of the bucket in which the value lies.   For an unsuccessful search, print an appropriate message and return a pointer to the leaf node in which the item should be inserted, along with the position it should be inserted into.
• P                                     To print out the contents of each node in the tree, by following a modified preorder traversal, as discussed in class and in the lab.  When this traversal visits a node, it will print all the contents of the node by looping through its data array in increasing order.  The recursive calls to the children of the node will be done by looping through the array of children pointers from the 0 index on up.

You will, of course, need to create a B+-Tree class that has at least the following member functions:

• Constructor
• Destructor
• Insert
• Delete
• Search
• Print

Output: Send your output for this program to a file.  For inserts, it is an error to insert a duplicate value in the B+-Tree structure, be sure to notify the user of such an attempt.  Tell the user if an operation is successful, as well.  Be sure to give appropriate "error" messages back to the user of your program, via the output file.  For e.g., if asked to delete a value from the B+-Tree structure that is not found in the structure, you should reply that the value was not found and so could not be deleted.  

Also Note: You are responsible to write a program that deals with *all cases*.  That is, your program should not only *work good on some input files*, it needs to work on *all possible* input files.  This means it is not your TAs responsibility to give you an input file that allows your program to work.  It is your responsibility to write code that cannot be broken by any input file and so will work in all cases.  This will be the case for every program you write for this course.

Extra Credit:  If you implement the B+ Tree for a general order, to be specified at run-time, then you will receive up to 10% extra credit for a possible score of 110% on the program.

A sample file follows that adheres to the input file format:

A  46

A 55

A 88

P

S 46

S 99

A 99

D 50

S 200

A 200

D 55

P

A 120

A 200

A 300

A 400

A 500

A 12

A 59

A 62

A 99

A 98

A 93

A 47

A 88

A 100

A 29

A 35

A 54

A 33

A 22

A 331

A 342

A 302

A 999

A 445

A 999

A 532

A 501

A 444

S 300

P

D 600

D 500