JamesMadisonUniversity

Computer Science Department

CS 239 Lab 1: Testing, Debugging, Documenting

Objectives:
  1. To help students to see the importance of both method documentation and inline commenting in working with code.
  2. To give students practice in working through the debugging process and in building test cases.

Background:

This program will read in a 3 character expression which happens to be in what is called postfix notation (i.e. the operator follows the operands) and displays it in what is called infix notation (i.e. the operator is placed in between the two operands).

Example of infix: 1+a

Example of postfix: 1a+

The operands in this program are single digits in base 16 notation (i.e. the acceptable digits are: 0123456789abcdef)

The final output of the program is the original expression in infix notation with the result shown in to base 10.

Note: one of the objectives is to have you debug code; so here you have a program that does not work properly. There are compiler errors as well as logic errors in the code. Your job today is to correct those errors and to properly document this code so that those that follow behind you can more easily make changes.

This program will only allow the single digit operands shown above (0 - f) and the operators + and -. The code should print an appropriate error message and abort (with a System.exit(x)) if these specifications are not met.

New Terms:

Test case - a single instance of data to test a program. A test case includes the input and the expected output or program behavior.

Materials:

Postfix.java

TestWorksheet

Acknowledgment

From an original lab by Arch Harris

1 Instructions

  1. Set up your programming environment for this lab.  This means that you should create a folder on the novell drive, on your flash drive, or in C:\temp and  name it  CS239-Lab1  Put  all of your work for this lab in it.  If you use  C:\temp, at the end of the lab period, put your work in the Blackboard drop box and erase it from temp.so that it will not be available to others.
  2. Download the above listed program and TestWorksheet to your folder.
  3. Read the problem description above again carefully.
  4. Open the TestWorksheet and fill in as many distinct tests cases as you can on it. A sample test case is shown on the first line of the worksheet.  Note that there is a section for tests of invalid as well as valid data on the worksheet.   Also note that 34+ is not a distinct test case.
  5. Open the Postfix.java program.
  6. Alter the header to include your name and date using javadoc style documentation.
  7. Add in white space and indenting to help you understand the current structure of the program and to help whoever will be grading your program read it easily.
  8. Correct the compiler and logic errors. Add inline comments as you understand what a section of code is intended to do. NOTE: it helps if you write these comments BEFORE you change the code. You may NOT delete sections of code, but must work within the structure provided.
  9. Compile and test your code after each change you make.
  10. Add lines with labels that echo each input value.  This will be a requirement for this, and most of the programs you will write this semester is to echo any input with labels.
  11. When you THINK you’re done, add additional test cases that you think will work and some that won’t work to your TestWorksheet.
  12. Turn your TestWorksheet in to your lab instructor at the end of the lab period.
  13. Submit your corrected code to the Blackboard Assignment noon Tuesday, August 26. Be sure to keep a copy of your submission.

2 Evaluation

Your lab will be evaluated based on:

Updated 08/22/08 (esa)