Due date: See Class Webpage

1. "Nano" Numbers

The people on planet Neptune (let's suppose there are people on Neptune) use the "Nano" number system that is based on the number 9. These creatures use the following symbols for digits:

Digit # ! % @ ( ) [ ] $ Value of the digit = 0 1 2 3 4 5 6 7 8

Their number system is positional, meaning that when a number contains multiple digits, then the value of a digit is equal to 9 times the successor digit.

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

Examples:

Nano number Value represent (in human decimal system) -------------- ------------------------------------------- ! 1 !# 9 !! 10 !% 11 !@ 12 !## 81 !#! 82 !#% 83 % 2 %# 18 %! 19 %% 20 (@ 39 (( 40 [[ 60 -[[ -60 And so on....

2. Preparation

• To do this project, you must obtain a copy of the prepared files with these commands on a lab machine:

  mkdir ~/cs255/pj3 cp /home/cs255001/Handouts/pj3/* ~/cs255/pj3

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• If you have Java install on your PC, and you want to work from home, you must download all the files in your ~/cs255/pj3 directory into your PC (you should create a cs255/pj3 directory in your PC to store the files)

  If you do work from home on your PC:

  After you have completed the project, you must upload your program(s) into your ~/cs255/pj3 project directory in Emory so that you can turn in your code (using the command given at the end of this handout).

  I do not accept email turnins !

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

  pj3.java: The main program that is used to test the 2 methods that you need to write for this assignment Do NOT change this file Nano.java: The Java class file that implements the 2 conversion methods specified in this assignment

3. Assignment

Write a Java class Nano that contains the static methods:

int parseNano(String s) without using Integer.parseInt(String s, int radix) Java library method. (Because the parseNano( ) method in this project is basically the Java's library's Integer.parseInt(String s, int radix) method using the symbols # ! % @ ( ) [ ] $ for the digits 0, 1, 2, ..., 8) and String toString(int value) without using 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 symbols # ! % @ ( ) [ ] $ for the digits 0, 1, 2, ..., 8)

which allows you to convert between:

"Nano" number representations (denoted as a string using the Nano digits, such as "@#!"), and int (which uses the 2's complement binary numbers) used by the computer.

The Nano class definition looks like this:

public class Nano { /* ========================================================== Return the 2's complement binary representation for the Nano number given in String s ========================================================== */ public static int parseNano(String s) { ... } /* ========================================================== Return the String of Nano 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 parseNano(String s) method converts a "Nano" number (stored as String s) into a 2's complementary int number.

  Examples:

  parseNano("#") returns the 2s compl representation for value 0 parseNano("!") returns the 2s compl representation for value 1 parseNano("-!") returns the 2s compl representation for value -1 parseNano("%") returns the 2s compl representation for value 2 parseNano("-%") returns the 2s compl representation for value -2 parseNano("!#") returns the 2s compl representation for value 9 parseNano("!!") returns the 2s compl representation for value 10

  (Recall that int uses the 2's complement number encoding scheme)

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• The String toString(int value) method converts a 2's complementary int number (in the input parameter value) to a "Nano" number (which is represented as String of Nano digits)

  Examples:

  toString(0) returns the String: "#" toString(1) returns the String: "!" toString(2) returns the String: "%" toString(9) returns the String: "!#" toString(10) returns the String: "!!"

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  Note to students:

  Some students in previous classes thought that because we write: Nano.toString(10) Nano.toString(16) Nano.toString( x ) that the Nano.toString() method receives a decimal number as a parameter. (decimal number = a positional representation for whole numbers based on the number 10) That is wrong !!! The data type int in Java contains a binary representation (everything stored in the computer are in binary) !!! In fact, Java uses the 2's complement encoding to represent the int data type. The following binary representations are passed as parameter in the method calls: Java statement: input parameter (int = 4 bytes) ----------------------- --------------------------------------- Nano.toString(10) 00000000 00000000 00000000 00001010 Nano.toString(16) 00000000 00000000 00000000 00010000 The reason is: The Java compiler is to help you write a program that the computer can execute. This includes representation of numbers used in the program !!! Humans likes to see (use) a whole value represented in the decimal number system So: the value ********** (= 10) is represented as 10 and we like to write it that way. The same whole value ********** (10 dots) must be represented inside the computer as: 00000000000000000000000000001010 So when you write this in Java: Nano.toString(10) // 10 in decimal The Java compiler will translate the representation of 10 into: 00000000000000000000000000001010 !!!

4. Test programs

• The handout contains 3 test programs:

  ParseNanoTest.java: This program only tests the parseNano( ) method Use this test program when you are writing the parseNano( ) method Compile with: javac ParseNanoTest.java Run test program with: java ParseNanoTest 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 pj3.java: This program allow you to enter two arbitrary Nano numbers; add them and print the result out as a Nano number. Use pj3.java only when you pass the above test programs !!! See Section 5 on how to use pj3.java

5. Compile and run pj3.java

• To compile the pj3.java test program (after you have passed the ParseNano.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 Nano numbers and then:

  Print out the values of the Nano number in decimal And then print the sum in Nano number representation

  Example 1: (my inputs are in red)

  For your convenience, here are the Nano digits: Nano digit: # ! % @ ( ) [ ] $ Value of digit: 0 1 2 3 4 5 6 7 8 Enter first Nano number x = @ The value of this Nano number in decimal system = 3 Enter second Nano number y = ) The value of this Nano number in decimal system = 5 The sum in decimal number system = 8 The sum in Nano number system = $

  Example 2: (my inputs are in red)

  For your convenience, here are the Nano digits: Nano digit: # ! % @ ( ) [ ] $ Value of digit: 0 1 2 3 4 5 6 7 8 Enter first Nano number x = !%@ The value of this Nano number in decimal system = 102 Enter second Nano number y = )() The value of this Nano number in decimal system = 446 The sum in decimal number system = 548 The sum in Nano number system = [[$

  Example 3: your program must handle negative values !!!

  For your convenience, here are the Nano digits: Nano digit: # ! % @ ( ) [ ] $ Value of digit: 0 1 2 3 4 5 6 7 8 Enter first Nano number x = !%(]($ The value of this Nano number in decimal system = 75698 Enter second Nano number y = -$$@)#( (Negative value !!!!) The value of this Nano number in decimal system = -527476 The sum in decimal number system = -451778 The sum in Nano number system = -])][()

6. Turn in ********************************** You must do this !!!

• Turn in your Nano.java program using a lab machine SOURCE file using the commands:

  cd ~/cs255/pj3 /home/cs255001/turnin Nano.java pj3 // IF you're in section 1 or: /home/cs255002/turnin Nano.java pj3 // IF you're in section 2

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• Extension request
  • To request an extension for pj3, you must execute the following command on a lab machine before the deadline of the homework:

    /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

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.