CIS 67: Homework 5

Handed out: 09/27/2005
Due: by 10:00pm on 10/03/2005
Email program to TA

The SOUNDEX code was devised by Margaret K.Odell and Robert C.Russell [US Patent 1261167 (1918) 1435663 (1922)]. The purpose of the SOUNDEX system is to classify together names that have similar sounds. It was used starting with the FD Roosevelt presidency to facilitate collection, collation, and retrieval of citizen's census information. (The algorithm is case insensitive, so we can and should convert all letters to uppercase.)

Here is the SOUNDEX algorithm as reported by Donald Knuth [The Art of Computer Programming, Volume 3]:

• Assign numbers to the letters after the first according to the rules below:
  • B,F,P,V -> 1
  • C,G,J,K,Q,S,X,Z -> 2
  • D,T -> 3
  • L -> 4
  • M,N -> 5
  • R -> 6
• If two or more letters with the same code are adjacent, omit all but the first.
• Retain the first letter of the name, and drop all occurrences of A,E,H,I,O,U,W,Y in other positions.
• Convert your result to the form, "letter, digit, digit, digit" by adding trailing zeros (if there are less than three digits), or by dropping rightmost digits (if there are more than three).

Here are examples of applications of the Soundex algorithm (also from Knuth):

	Euler		-> E460
	Gauss		-> G200
	Hilbert		-> H416
	Knuth		-> K530
	Lloyd		-> L300
	Lukasiewicz     -> L222
	Pfister		-> P236

Write a class Soundex whose main function in a loop prompts the user to enter a name and then prints out the soundex code for that name. The loop terminates when the name entered is the empty string.
Implement and use in your program the method

	static String getSoundex(String s);

	static char encode(char c);

Be sure to document your code and to write your name in the java file.