CSC 171
Homework 1

Assigned Feb 1, due Feb 11

Reading and Reactions

• Read The Joys (and Woes) of the Craft of Programming.

• Read the article on Pair Programming.

• Watch a brief video on Pair Programming (available in MOV and WMV formats). The narration is a little kitschy, but informative.

• Skim Adages on Software Design and Development (I expect you to read all this stuff eventually, at your own pace.)

• Write a few paragraphs on your reaction to the above reading assignments, and turn them in by email to Dr. Bloch. Be sure to include your name!

• Make an appointment by e-mail to see Dr. Bloch in his office for 5 minutes. (This makes sure you have my e-mail address, I have your e-mail address, you know where my office is, I can learn to attach your name to your face, and we can discuss our expectations of the class one-on-one.)

Programming

This looks like a lot of methods to write, but each one is pretty short and simple. They'll probably each be ten to twenty lines long, and most of this is contracts, examples, and inventories.

For all the programming assignments, be sure to follow the design recipe. First, create a class; for now, all your methods will be in one class (let's suppose it's called Homework1. Then, for each method, follow the design recipe to design, code, and test it.

Be sure to choose meaningful names for methods and parameters, and watch for opportunities to re-use methods you, I, or the textbook have already written.

Also turn in a log of how many errors of different kinds you encountered in the assignment, with brief comments describing each one ("mismatched parentheses" is self-explanatory, but more complex errors might need more description). You may do this using the PSP forms, or simply by keeping track in a text file or on paper and turning it in.

How to turn this in

This part can be done from any computer that has BlueJ and our customizations installed, but it'll be easiest from your computer rather than a lab computer. Once you've written your methods and test cases, you should have two classes: Homework1 and Homework1Test. From BlueJ's "Tools" menu, choose "Submit..." (which should be at the bottom of the menu). Browse to "Computer Science Courses" -> "CSC 171 Introduction to Computer Science", then click the "Submit" button. It'll ask for your name and any message you want to attach, then (perhaps) your Adelphi e-mail address and password (it needs this in order to send mail). It will then package up all the classes in the current project and mail them to both Dr. Bloch and Dr. Stemkoski.

Methods to write

For now, I recommend putting all of these in one class (say, Homework1).

• Develop a method named twist which takes in an image and returns a 10-degree-rotated copy of it overlaid onto the center of a 10%-larger copy of it. Include a test case showing what happens when you call twist on the result of twist on the result of twist.

• Develop a method named caption which takes in an image, a String, and a number, and produces an image in which the specified String is overlaid on the image, with its center the specified number of pixels down from the top of the image (and on the center line).

• Develop a method named hoursToMinutes which takes in a number of hours and returns the number of minutes in that many hours.

• Develop a method named daysToHours which takes in a number of days and returns the number of hours in that many days.

• Develop a method named daysToMinutes which takes in a number of days and returns the number of minutes in that many days.
  Hint: re-use previously-written methods. You should be able to write this method with no numbers or arithmetic operators in the method body (although you'll need numbers in your test cases, of course).

• Develop a method named squarePerim which takes in the length of a side of a square, and returns its perimeter.

• Develop a method named circleArea which takes in the radius of a circle and returns its area. The formula is π r²; use the predefined variable Math.PI as the value of π.

• Develop a method named dhmToMinutes that takes in three numbers: how many days, how many hours, and how many minutes, in that order, and returns the total number of minutes.
  Hint: You should be able to write this with no numbers or multiplications in the body of the method, by re-using previously-written methods.

• Develop a method named celsiusToKelvin that takes in a number of degrees Celsius and returns the same temperature as written in Kelvin. (A degree Kelvin is the same size as a degree Celsius, but 0 Kelvin is approximately -273.15 Celsius. This gives you at least one example: Homework1.celsiusToKelvin(-273.15) should be about 0.
  Come up with at least two more examples of your own.) Note that the method should handle fractional degrees, not only integers.

• Develop a method named fahrenheitToCelsius that takes in a number of degrees Fahrenheit and returns the same temperature as written in Celsius. (The formula is C = (F-32)*5/9 .) For example, Homework1.fahrenheitToCelsius(68) should produce 20.

• Develop a method named fahrenheitToKelvin that takes in a number of degrees Fahrenheit and returns the same temperature in Kelvin.
  Hint: You should be able to write this with no numbers or arithmetic operators in the body of the method, by re-using previously-written methods.

• Develop a method named convert3digits that takes in the "hundreds", "tens", and "ones" digits of a number, in that order, and returns the number. For example, Homework1.convert3digits(5,2,8) should be 528

• Develop a method named convert3reversed that takes in the "ones", "tens", and "hundreds" digits of a number, in that order, and returns the number. For example, Homework1.convert3reversed(7,0,1) should be 107.
  Hint: You should be able to do this with no numbers or arithmetic operators in the body of the method, by re-using previously-defined methods.

• Develop a method named quadraticFormula that takes in the coefficients a, b, and c of a quadratic, and computes the value of the largest real root. You may assume that there is at least one real root. The formula is (-b+sqrt(b²-4ac))/(2a).

Grading standards

Office visit:         /5
Did you do it?

Essay:               /25
(Grading primarily on content: convince me that you've read the articles and some of the adages and thought about them.)

Error log:       /10
(I'm not grading on how many or how few errors you encountered, only on whether you recorded them adequately.)

Programming: To save time and get you feedback more quickly, I probably won't grade all of the methods, but a random selection of them. For each method, I'll award

• 5 points for the contract and purpose;
• 5 points for the test cases;
• 5 points for the skeleton and inventory;
• 10 points for the method body

General skills:

So if I were to grade 8 of the methods, the assignment would be worth 300 points: 5 for the office visit, 25 for the essay, 10 for the error log, 25 for each of 8 methods, and 60 for the "general skills".