lab11, CISC106, Fall 2007

Overview

This lab provides more practice with C++

You may want to review the idea of a "Design Recipe" from the following wiki pages:

• Design Recipes in MATLAB
• Design Recipes in C++

Prerequisites

Before starting this lab:

• You should already be comfortable with the skills from lab10.
• You should have kept up with the lectures on C++.

Step-by-Step Instructions

Step 1: Preparing your lab11 directory, and copying files you will need

Step 1a: Create a new subdirectory for lab11

Create a new subdirectory ~/cisc106/lab11, and make that your working directory.

Step 1b: Copy the files needed for this week's lab

The files for this lab are in the directory /www/htdocs/CIS/106/pconrad/07F/labs/lab11

Step 2: Examining the example programs

As in past weeks, there is nothing to turn in for Step 2

The work you do in step 2 of this lab is only for practice and learning. There is nothing to turn in from this step of the lab.

So you could skip it if you wanted to, and neither your instructor nor your TA would know.

Well, actually that's not entirely true.

We'd know if,

• you missed the exam questions that were based on this part of the lab
• you asked questions about step 3 that you should have already known if you had actually done this step.

So, don't skip this step.

Step 2a: A C++ files that defines a function: areaOfRect.cc

Previously, we've worked with M-files that define MATLAB functions.

In the lab11 directory, there is an example of a C++ files that defines a function: areaOfRect.cc

Take a look at this C++ source file. To test it out, we need to take several steps. We'll talk more about these steps in lecture, but you have enough here to get started:

The steps involved in defining functions in their own files in C++

1. write one or more driver program—for example:
   • the file testAreaOfRect.cc is a regression/acceptance test for areaOfRect.cc
   • the file rectPizza.cc is a driver file to compute price per square inch of a pizza
2. compile the areaOfRect.cc files into an object file areaOfRect.o

   CC -c areaOfRect.cc

3. compile each of our drivers into a .o file

   CC -c testAreaOfRect.cc
   CC -c rectPizza.cc

4. link the object files for our function definition and the object file for our driver into a single executable, with the following commands:

   CC areaOfRect.o testAreaOfRect.o -o testAreaOfRect		
   CC areaOfRect.o rectPizza.o -o rectPizza

5. run the executable
   • we do this with the command ./testAreaOfRect

You can also use g++, but you have to use either all CC or all g++. Within a given directory or project, you have to choose one compiler and stick with it. (You switch compilers half-way, but if you do, you need to use the rm command to delete all the .o files, and recompile everything from the beginning.)

Now you try it

Look at the code inside all three files:

Then try the steps outlined above, to see if you can produce the following output:

strauss.udel.edu% CC -c areaOfRect.cc
strauss.udel.edu% CC -c testAreaOfRect.cc
strauss.udel.edu% CC areaOfRect.o testAreaOfRect.o -o testAreaOfRect
strauss.udel.edu% ./testAreaOfRect
Test 1...passed
Test 2...passed
strauss.udel.edu% CC -c rectPizza.cc
strauss.udel.edu% CC areaOfRect.o rectPizza.o -o rectPizza
strauss.udel.edu% ./rectPizza
Please enter length of pizza: 10
Please enter width of pizza: 5
Please enter price of pizza: 7.99
Price per square inch is 0.16
strauss.udel.edu%   

Step 2b: Looking at the myMin.cc and testMyMin.cc files

Step 3: A function to compute price per square unit of a disc

Step 3a: Design a file areaOfDisc.cc

Write an C++ file, using the first three steps of the "Design Recipe" steps, that defines a function that computes the area of a disc (e.g. a pizza).

1. identify the contract (what type of data the function consumes, and what it produces) and write the function header and the comment preceding the function definition
2. come up with at least two examples, and document them in the comment preceding the function definition
3. develop the body of the function

It may be useful to consult the Wiki Page about Design_Recipes in C++ for additional help on how to proceed.

When your function is complete and it tests continue to the next step to test it, thus completing step 4 of the design recipe.

Step 3b: Write a regression test driver program: testAreaOfDisc.cc

Using the example programs testMyMin.cc and testAreaOfRect.cc as a model, write a regression test script for areaOfDisc.cc. Use your examples that you came up with in step 2 of the design recipe.

Refine your C++ source files areaOfDisc.cc and testAreaOfDisc.cc until all the tests pass.

Step 3c: Write an interactive driver roundPizza.cc

Using the example program rectPizza.cc as a model, write an interactive driver called roundPizza.cc that uses your areaOfDisc.cc function to compute the price per square inch for a round pizza.

Important Instructions (deductions will be made for failing to follow these instructions)

• Make your interactive driver specific to the problem of computing the price per square inch of a pizza. That is, the prompts to the user should specifically ask for the diameter in inches, and the price in dollars. The output should be labeled specifically as price per square inch for a round pizza.
• Do not embed the computation "area equals pi-r-squared" in the file roundPizza.cc
  • We are using the function areaOfDisc to do that computation. Learning how to separate out these two parts of the software is one of the main things you are supposed to be learning from this exercise.
• It is ok, however, to embed the division of price by area directly in the roundPizza.cc file
  • This is inconsistent with what we did in lab07—that's ok.
  • We could go a step further and define a function to compute price per square inch for a round object—and put that function in yet another file. However, I'm not requiring you to take that extra step.

Step 4: Create C++ files to define and test a function myMax

Step 4a: Design an C++ function myMax (stored in myMax.cc)

Use the Design Recipe to design a function myMax() and store it in a file called myMax.cc. This function should take an array of integers, and the number of integers in that array, and return the maximum number in that vector. It should operate in a manner similar to the myMin.cc function provided in the lab11 directory, which you may use as a model.

Step 4b: Design an C++ main program testMyMax.cc to do regression testing for myMax.cc

Following the steps outlined previously develop a regression testing file called testMyMax.cc to do regression testing on the function you developed in step 4a.

If you aren't sure what to do, review step 2

Step 5: Create a script file lab11.txt to show your work.

Making the script file lab11.txt

Once the programs developed for this lab work, create a script file called lab11.txt in which you type out each of the C++ files you developed in steps 3 and 4, and also demonstrate that they work properly.

• If you need a refresher on script files for C++, review the instructions at step 4 of lab10
• You should type your commands in your script file exactly in the order given below.

Order for Script file

1. Type out contents of areaOfDisc.cc
2. Type out contents of testAreaOfDisc.cc
3. Compile and link the two previous files together, and then run the resulting executable
4. Type out the contents of roundPizza.cc
5. Compile and link areaOfDisc.cc with roundPizza.cc and run the resulting executable
6. Type out the contents of myMax.cc
7. Type out the contents of testMyMax.cc
8. Compile and link these two files, and run the resulting executable

Step 6: Creating a zip file of your work

The following example shows how to create a zip file called lab11.zip containing all the .cc files in the directory lab11.

The example is followed by an explanation. The part you type is in bold.

strauss.udel.edu% pwd
/www/htdocs/CIS/106/pconrad/07F/labs/lab11
strauss.udel.edu% cd ..
strauss.udel.edu% pwd
/www/htdocs/CIS/106/pconrad/07F/labs
strauss.udel.edu% zip lab11.zip lab11/*.cc
  adding: lab11/areaOfRect.cc (deflated 48%)
  adding: lab11/rectPizza.cc (deflated 53%)
  adding: lab11/testAreaOfRect.cc (deflated 54%)
strauss.udel.edu% 

Explanation

• use cd .. to go one directory level higher than the one containing your .cc files.
• use the command zip lab11.zip lab11/*.cc to
  • create a new zip archive called lab11.zip
  • inside that archive, put a directory called lab11, containing all the files that end in .cc from your current lab11 directory

In your case, you should have five .cc files in all

• see the list in the section marked grading

Step 7: Upload and Submit your work on WebCT

This week, since we are using a zip file, you only have to submit two files:

• your lab11.zip file (containing five C++ programs), and
• your lab11.txt file (the script file with all the runs)

A few important DOs and DON'Ts

• DO be sure that your zip file contains ONLY C++ source files
• DON'T include .o files, or executables in your zip file
• DO upload your lab11.txt files separately from your lab11.zip file
  • This is important to make grading convenient for your TA. Take pity--he/she may have 80 students papers to grade for every single lab!
• DON'T include your lab11.txt file inside your lab11.zip file, and then upload only that one file.
  • This makes your TAs life more difficult, and he/she will keep that in mind when assigning a grade!

That's it for lab11!

Due Date: Thu, 11/29/2007 11:55pm

Grading: 100 pts

1. areaOfDisc.cc (20 pts)
2. testAreaOfDisc.cc (10 pts)
3. roundPizza.cc (10 pts)
4. myMax.cc (20 pts)
5. testMyMax.cc (10 pts)

• general programming style issues: commenting, formatting, indenting, variable names (20 pts)
• following directions (e.g. correct order in the lab11.txt diary file, correct filenames, etc.) (10 pts)

End of lab11 for CISC106, Fall 2007