EECS 360 - Machine Problem 4

Hashing

Due: 11:59 pm on Thursday 10/26/2000

For this assignment you must work alone.

For this assignment, you are to add, find and remove strings from a open addressing hash table.  The hash table will be allowed to change size, but must always have a prime number for its size. The initial size of the hash table is to be 53.  To resolve collisions, we will use a double hashing routine.  The primary hash function to be used is the one discussed in the book in firgure 5.5.  The secondary hash routine used with the double hashing routine is to use the next smallest prime number from the size of the table for the value of R in the formula discussed in class and the book.

The program is to be interactive.  The commands will be similar to what was used in MP3.  The biggest difference is that the values used will be strings and not integers.  The next difference is that white space will be used instead of commas to seperate multiple
strings.  We will implement the following operations:
 

a <el1> <el2> <el3> ... <elN>
Add all N elements to the hash table. If a collision occurs while adding the element, print a message stating the number of hash table positions that had to be examined before the element could be inserted.  An error message should be printed if an element that is already in the hash table is attempted to be added.  The elements are to be added to the hash table in the order they are given.
c
Clear all elements from hash table.
f <el1> <el2> <el3> ... <elN>
Find all N elements in the hash table. For each element, print a message whether the element was found or not found.
r <el1> <el2> <el3> ... <elN>
Remove all N elements from the hash table. An error message should be printed if an element that is not in the hash table is attempted to be removed. If a collision occurs while deleting the element, print a message stating the number of hash table positions that had to be examined before the element could be deleted.   The elements are to be removed from the trees in the order they are given.
s  <int>
The hash table to change size to be the next largest prime number greater than or equal to the integer value given in the command.  The current hash table is to be "rehashed" into the hash table of this new size.  You must use dynamic array allocation to create the new hash table and deallocate to old hash table when it is no longer needed.  When the command is finished print a meesage stating how many collosions occurred during the rehashing operation.
w <filename>
Write out the contents of the current hash table to the indicated file.  The first line of the file should have the string stored at position zero and the last line of the file should have the string stored a position (size -1).  The file should the hash table position listed before the string is printed.  You may (but are not required to) print out the "KindOfEntry" information associated with that position after the string.
i
List the current size of the hash table, the number of elements in the hash table, the percent of positions that have an element.
q
Quit the program. Print an appropriate good-bye message upon completion of your program.

 
The input for the program will be given through standard input. Each line of input will have one and only one operation. Each operation will fit on one line of input. You may assume that each line is no more than 100 characters long. The first non-white space character will be the character for the operation. If an unknown character is given, print out an error message such as Operation X is not known and ignore the rest of the the input line. White space characters are the space an tab characters.  You may assume that each string is 30 characters or less in length.

Since this program is to be interactive, your program is to prompt the user for each command.

General Comments


Your program must be written in good programming style. This includes (but is not limited to) meaningful identifier names, a file header at the beginning of each source code file, a function header at the beginning of the function, proper use of blank lines and indentation to aide in the reading of your code, explanatory "value-added" in-line comments, etc.

The work you turn in must be 100% done by your own own. You are not allowed to share code with any other students (inside this class or not). You may discuss the project with other students; however, you may not show any code you write to another student nor may you look at any other student's written code.

You are to submit this project using the EECS Department's UNIX machine's turnin command. The project name for this assignment is mp4. Be sure to submit all source code and header files and makefile. Failure to turnin all required pieces will result in a lower grade for the assignment. The turnin command for this assignment is: 

     turnin -c eecs360a -p mp4 <file list>
where <file list> is the names of all files that you will submit for this program. You can use the turnin command multiple times; however, ever time you must submit all files needed for the program. To see which files you have submitted to turnin use the -v option with the turnin command as follows: 
     turnin -c eecs360a -p mp4 -v