Overview

The purpose of this lab is to provide students an opportunity to work closely with algorithms for changing number bases.

Activities

• Read Section 1.4 in the textbook.
• Review supplemental videos 2 - 5.
• Write and solve 10 base conversion problems.
• Write a number conversion program

Practice Problems

Write and solve 10 (or more) different number conversion problems.

• Five of the problems should have you convert from base 10 to another base.
• The remaining five should have you convert to base 10.
• Each base may be used at most once.
• You may use a web site like www.geogebra.org/m/ZEdZjfxm to check your answers. (Show enough work to convince me that you did more than simply copy answers from the web page.)

Submit a document showing your problem, your work, and your solution.

Practice Problems

Use the provided Java starter code to write a conversion method that will take in a string representing a number in a specified base and convert it to another base. Do not worry so much about catching error conditions; for this lab it is more important to learn the number conversion process and implement the algorithm.

Restrictions:

• Use the names provided in the starter code. Do not change the class name or method signatures.
• You are not allowed to use Integer.parseInt(String, int) any other library code that completes a significant portion of the assignment.

The provided starter code contains a class in the default package named NumberBase with the method public static String convert(String input, int base_in, int base_out). This method takes the number represented by the input and converts it from base_in to base_out. For example, NumberBase.convert('ff',16,10) returns "255".

Assumptions:

• input will be a string representing a number in the range of 0 to 2³¹-1
• base_in and base_out fall between 2 and 36 (inclusive)
• For bases over 10, use lowercase letters (Tests will fail and credit not given for uppercase!)
• The return should be a string containing the answer with no leading zeroes.
• Do not worry about illegal input.

Files:

• The start code: NumberBase_Stub.java. (Please change the name of this file to something without Stub in it.)
• Sample test class: NumberBaseTest_Sample.java. You can use this as a starting point for tests; but, you must add tests of your own. (Please change the name of this file and class to something without Sample in it.)
• Necessary .jar files:
  • junit-4.12.jar
  • hamcrest-core-1.3.jar

Testing: I will use a JUnit test similar to NumberBaseTest_Sample.java to test your code. Be sure to thoroughly test your code using JUnit or other automated test framework. (The sample JUnit test is designed to ensure you named your classes and methods properly. It is up to you to extend it to thoroughly test your code.)

The test will not run unless you follow the directions above. If a class or method name is misspelled, the method signature (arguments, return value) changed, or visibility of the class and method are changed, the tests will not run and I will deduct points.

You may write, compile, and run your code using any IDE you prefer. However, there is a good chance I won't be able to help you if you have configuration problems. I will run and test your code from the EOS command line using commands similar to these:

• javac NumberBase.java
• javac -cp junit-4.12.jar:hamcrest-core-1.3.jar NumberBaseTest.java
• java -cp hamcrest-core-1.3.jar:junit-4.12.jar:. org.junit.runner.JUnitCore NumberBaseTest

(I'm a command line nerd; so, I'm happy to explain how/why these commands work.)

Submission and Grading:

• You must demonstrate your code to me before you submit it.
  • If you finish during the lab session, please raise your hand and call me over to check the functionality of your program.
  • If you do not finish during the lab session, you must stop by my office and demonstrate your code before the due date.
• Once I have approved your code, please submit your code and tests on Blackboard (only one submission per group). Make sure all Java files contain both group members' names in a comment. Note: Code should also be well formatted and legible so that I can evaluate it.

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