Due date: See Class Webpage

1. Preparation

• To do this project, you must obtain a copy of the prepared files with the usual procedure.

  Use the project code pj3 to get the files for Project 3.

• The files that you have copied into your ~/cs255/pj3 directory should be these:

  ParseDuoDecTest.java: This program is used to test the parseDuoDec( ) method Do NOT change this file ToStringTest.java: This program is used to test the toString( ) method Do NOT change this file pj3.java: This program lets you experiment further with Base 12 numbers Do NOT change this file DuoDec.java: The Java class file that implements 2 conversion methods (called: parseDuoDec( ) and toString( )) specified in this assignment You must edit this file for pj3

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• Project 3 is a Java programming project.

  You can work on project 3 in the following ways:

  The easiest way to work on project 3 is to use EGTAPI. You can work on project 3 remotely from your laptop with EGTAPi Watch this video on how to use EGTAPI to do so: click here If you know (1) how to use an editor in the UNIX (Ubuntu Linux) platform and (2) how to use javac compile Java programs; then you can use this 2nd method. The 2nd way is to use a ssh client application to login to a lab machine. On a Windows PC, you need to the MobaXTerm application - which contains a ssh client application. On a Mac PC, you need to open a terminal and execute the ssh command (Mac provides a ssh client application). Instructions on how to install the necessary software and how to login to an Emory lab workstation are given on Canvas. If you know how to transfer files between Emory and you PC, you can use the 3rd method to work on project 3. NOTE: Instructions to install and use the software to perform file transfer between your PC and Emory is given on Canvas You must also have installed a Java compiler on your laptop. To work on project 3 on your laptop, you must do the following: Transfer all the files from your Emory's ~/cs255/pj3 folder (directory) onto your PC - (you should create a cs255 directory in your PC to store the files) Work on the copy of the file DuoDec.java on your PC After you have completed the project, you must transfer the DuoDec.java program file on your PC back to your Emory's ~/cs255/pj3 folder

  Important note: No matter how to decide to work on project 3, you must turn in the DuoDec.java program file for project 3 using the TURNIN procedure given at the end of this handout - click here to see the turnin instructions.

  I do not accept email turnins (there are too many students in CS255, I can't handle that many emails !)

2. Introduction: Duodecimal Numbers (See: Wikipedia page)

The people on planet Mars (let's suppose there are people on Mars) use the Duodecimal number system that is based on the number 12 - I will call these numbers "Duodec" numbers for short. The Martians do not use the human-way to denote digits (as you know, human use: 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9) - the Martians use the following symbols for digits:

Digit @ ! ? & % $ = ^ ( ) [ ] Value of the digit = 0 1 2 3 4 5 6 7 8 9 10 11

Their number system is positional, meaning that when a number contains multiple digits, then the value of a digit is equal to 12 times the successor digit.

It happens that Marsians use the minus sign '−' to denote negative values

Here are some examples of how the Marsians write their Duodeciaml numbers and the corresponding value:

DuoDec number Value represent (in human decimal system) -------------- ------------------------------------------- @ 0 ! 1 ? 2 ) 9 ] 11 !@ 12 !! 13 != 18 ?! 25 [[ 130 -[[ -130 [[[ 1570 -[[[ -1570 And so on....

In this project, you will write 2 conversion methods for DuoDec numbers in Java. The parseDuoDec( ) method will convert a string input in DuoDec numbers into 2s complement (binary) representation (for calculation purpose) and the toString( ) method will convert a 2s complement (binary) representation into a string of DuoDec digits (for output purpose)

These 2 methods will enable a Java program to read in Duodec numbers from the keyboard, then perform computations (in 2s complement) and then print results of computations in the Duodec number system representation.

3. Assignment

Write a Java class DuoDec that contains the static methods:

int parseDuoDec(String s) This method receives a DuoDec number string and returns the value represented by this string. E.g.: parseDuoDec("!") will return the value 1. Requirement: you cannot use the Integer.parseInt(String s, int radix) Java library method. (Because the parseDuoDec( ) method in this project is basically the Java's library's Integer.parseInt(String s, int radix) method using the special symbols @ ! ? & % $ = ^ ( ) [ ] for the digits 0, 1, 2, ..., 11) String toString(int value) This method receives an integer value and returns the string representation in DuoDec number system. E.g.: toString(1) will return the string "!". Requirement: you cannot use the Integer.toString(int i, int radix) Java library method. (Because the toString( ) method in this project is basically the Java's library's Integer.toString(int i, int radix) method using the special symbols @ ! ? & % $ = ^ ( ) [ ] for the digits 0, 1, 2, ..., 11)

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I have provided the skeleton function code of these methods in the handout file DuoDec.java (you would have made a copy of this file using the above instructions). Take a look in the file DuoDec.java and you will see that the DuoDec class definition looks like this:

public class DuoDec { /* ========================================================== Return the 2's complement binary representation for the DuoDec number given in String s ========================================================== */ public static int parseDuoDec(String s) { ... } /* ========================================================== Return the String of DuoDec digit that represent the value of the 2's complement binary number given in the input parameter 'value' ========================================================== */ public static String toString(int value) { ... } }

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• The int parseDuoDec(String s) method is used to convert a "DuoDec" number represented as String s into a integer int value (i.e.: a 2s complement code !).

  Examples:

  parseDuoDec("@") returns the 2s compl representation for value 0 parseDuoDec("!") returns the 2s compl representation for value 1 parseDuoDec("-!") returns the 2s compl representation for value -1 parseDuoDec("?") returns the 2s compl representation for value 2 parseDuoDec("-?") returns the 2s compl representation for value -2 parseDuoDec("!@") returns the 2s compl representation for value 12 parseDuoDec("!!") returns the 2s compl representation for value 13

  (You should know that int data type uses the 2's complement number code to represent the value !)

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• The String toString(int value) method converts a 2's complementary int number (in the input parameter value) to a "DuoDec" number string (= a String of DuoDec digits)

  Examples:

  toString(0) returns the String: "@" toString(1) returns the String: "!" toString(2) returns the String: "?" toString(12) returns the String: "!@" toString(13) returns the String: "!!" toString(-13) returns the String: "-!!"

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  Note to students:

  Some students in previous classes thought that because we write: DuoDec.toString(4) DuoDec.toString(16) DuoDec.toString( x ) that the DuoDec.toString() method receives a decimal number as input parameter. (So they are confused: why do I ask them to write a toString( ) method that converts 2s complement representations for input values). This is wrong !!! The DuoDec.toString() method does NOT has a decimal number as input parameter. Remember that the compiler translates every (decimal) number that we write in the source program into 2s complement representation: When you write: x = 4; The Java compiler will store the binary number 00000000 00000000 00000000 00000100 in the variable x Therefore, when you write: DuoDec.toString(4); The Java compiler will convert "4" into the binary number 00000000 00000000 00000000 00000100 and then pass it to the function !

4. Test programs

• The handout contains 3 test programs:

  ParseDuoDecTest.java: This program only tests the parseDuoDec( ) method Use this test program when you are writing the parseDuoDec( ) method Compile with: javac ParseDuoDecTest.java Run test program with: java ParseDuoDecTest You program passed the test if you see this message: Single digit duodecimal number tests.... Single digit duodecimal number tests.... PASSED ! Two digits duodecimal number tests.... Two digits duodecimal number tests.... PASSED !! Three digits duodecimal number tests.... Three digits duodecimal number tests.... PASSED !! Large duodecimal number tests.... Large duodecimal number tests.... PASSED !! ---- All parseDuoDec tests passed ! ToStringTest.java: This program only tests the toString( ) method Use this test program when you are writing the toString( ) method Compile with: javac ToStringTest.java Run test program with: java ToStringTest You program passed the test if you see this message: Single digit duodecimal number tests.... Single digit duodecimal number tests.... PASSED ! Two digits duodecimal number tests.... Two digits duodecimal number tests.... PASSED !! Three digits duodecimal number tests.... Three digits duodecimal number tests.... PASSED !! Large duodecimal number tests.... Large duodecimal number tests.... PASSED !! ---- All toString tests passed ! pj3.java: This program allow you to enter two arbitrary DuoDec numbers; add them and print the result out as a DuoDec number. Use pj3.java only when you pass the above test programs !!! See Section 5 on how to use pj3.java

5. Explore the strange world of base-12 numbers using pj3.java

• I provided this test program to let you play around with the duodecimal numbers using the strange digit notations.

  This program allow you to enter two arbitrary DuoDec numbers and it will add them and print the result out as a DuoDec number. You can see for yourself that the addition works in this strange number system.

• To compile the pj3.java test program (after you have passed the ParseDuoDec.java and ToStringTest.java tests), use:

  javac pj3.java

• After the compilation is successful, you can run the program using:

  java pj3

  The program will ask you to enter 2 DuoDec numbers and then:

  Print out the value of the DuoDec numbers that you have entered in binary and decimal And then print the sum in DuoDec number representation

  Example 1: (my inputs are in red)

  Here are the DuoDec digits: DuoDec digit: @ ! ? & % $ = ^ ( ) [ ] Value of digit: 0 1 2 3 4 5 6 7 8 9 10 11 Enter first DuoDec number x = & Debug: x = 00000000000000000000000000000011 Debug: the decimal value = 3 Enter second DuoDec number y = ^ Debug: y = 00000000000000000000000000000111 Debug: the decimal value = 7 Debug: x + y = 00000000000000000000000000001010 Debug: x + y = 10 (in decimal) x + y = [ (in DuoDec) (Check the DuoDec string for correctness !)

  Example 2: (my inputs are in red)

  Here are the DuoDec digits: DuoDec digit: @ ! ? & % $ = ^ ( ) [ ] Value of digit: 0 1 2 3 4 5 6 7 8 9 10 11 Enter first DuoDec number x = () Debug: x = 00000000000000000000000001101001 Debug: the decimal value = 105 Enter second DuoDec number y = -] Debug: y = 11111111111111111111111111110101 Debug: the decimal value = -11 Debug: x + y = 00000000000000000000000001011110 Debug: x + y = 94 (in decimal) x + y = ^[ (in DuoDec) (Check the DuoDec string for correctness !)

6. Extension request

• The easiest way to request an extension is using EGTAPI. See instructions in homework 1 handout write up: click here.

  However, you need to use pj3 as homework code to make extension for this homework/project.

• Alternately, you can request an extension for pj3, by executing the following command in EGTAPI's console:

  /home/cs255001/req-ext pj3 // IF you're in section 1 or: /home/cs255002/req-ext pj3 // IF you're in section 2

  You request will be successful if you have not exceeded the maximum number of "free" (no-questions-asked) requests allowed

7. How to turnin your project

Important note:

You must turn in your DuoDec.java file to complete the assignment !!! You can turn in your work using EGTAPI

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• In CS255, you must turn in your assignments (in this case the file pj3.s) electronically by using the the following turnin procedure before the due date:

  1. Click on File Browser in EGTAPI 2. Select the file that you want to turn in In this case, select the file "DuoDec.java" inside your pj3 folder 3. After selecting the file (in this case: "DuoDec.java"), click Turnin in the File Browser menu The "Egtapi Turn-in" window will pop up 4. In the "Section Number" drop down tab: Select "1" if you are in Section 1 Select "2" if you are in Section 2 5. Enter "Project Code": pj3 6. Click the "Turn in" button 7. You will see the turn in result in the right most panel. Make sure that your see the message: "Program ... has been successfully turned in..."

  Alternately, you can turn in your file using the EGTAPI Terminal:

  1. Open the EGTAPI Terminal (click on "Terminal") 2. Enter these command in the lower input area of the Terminal panel: (a) cd ~/cs255/pj3 (go to your pj3 folder) (b) /home/cs255001/turnin DuoDec.java pj3 // If you're in section 1 or (b) /home/cs255002/turnin DuoDec.java pj3 // If you're in section 2

  If you want to see what you have turned in, then

  1. Open the EGTAPI Terminal (click on "Terminal") 2. Enter this command in the lower input area of the Terminal panel: /home/cs255001/turnin // If you're in section 1 or /home/cs255002/turnin // If you're in section 2

Students will be graded partially on the basis of their homework assignments. These homework assignments are to be treated as examinations, and are expected to be your individual work. While discussions with other students in the course may be permitted or encouraged by your instructor, you should write your program yourself. Your instructor (and any teaching assistants assigned to the course) will be glad to help you to the extent that he or she feels reasonable. Submissions based on other students solutions in prior offerings of the course specifically violate these guidelines, as do submissions prepared with the help of an outside "tutor". You should take precautions to protect the confidentiality of your work, do not collaborate on questions that you turn in for a grade, do not show your solution to a fellow student, not even after the due date for some students may have receive extension. All submissions should include a comment statement near the top of the program of the form:

THIS CODE IS MY OWN WORK, IT WAS WRITTEN WITHOUT CONSULTING A TUTOR OR CODE WRITTEN BY OTHER STUDENTS - your name

Cases of apparent plagiarism or collusion will be referred to the Honor Council.