CSC 171
Homework 1

Assigned Jan 27, due Feb 6

Surveys

Fill out the pre-semester background survey on the Web.

Fill out the daily survey on the Web, at least once with your name. (In general, I'd like you to fill it out at least once a week, preferably after every class, name optional.)

Reading and Reactions

• Read, in How to Design Programs, from the preface through chapter 4 (by Wednesday, Feb. 1).

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

• 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 5-10 minutes. (This makes sure you have my e-mail address, I have your e-mail address, you know where my office is, and we can discuss our expectations of the class one-on-one.)

Programming

For all the programming assignments, be sure to follow the design recipe. Write your function contract, examples, and function definition in the Definitions Window, save it to a file, and e-mail me this file. Also test your program: since you've already included examples in the Definitions window, you should be able to hit the Execute button and see all the results (along with what you said they "should be"). Save the resulting Interactions window to a text file and e-mail me this file too. Be sure to choose meaningful names for functions and parameters, and watch for opportunities to re-use functions 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.

• Develop a function named hours->minutes which takes in a number of hours and returns the number of minutes in that many hours.
  (We did this in class, so just copy it out of your notes.)

• Develop a function named days->hours which takes in a number of days and returns the number of hours in that many days.

• Develop a function named days->minutes which takes in a number of days and returns the number of minutes in that many days.
  Hint: re-use previously-written functions. You should be able to write this function with no numbers in the definition (although you'll need numbers in your examples, of course).

• Develop a function named dhm->minutes which 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: re-use previously-written functions. You should be able to write this, too, with no numbers in the definition.

• Develop a function named f->c which takes in a temperature in degrees Fahrenheit and returns the same temperature expressed in degrees Celsius.
  (The formula is C = (F-32)*5/9; we did this in class too.)

• Develop a function named c->k which takes in a temperature in Celsius and returns the corresponding number of degrees Kelvin. (A Kelvin degree is the same size as a Celsius degree, but Kelvin's 0 is the same as -273 Celsius, so 0 Celsius is 273 Kelvin.)

• Develop a function named f->k which takes in a temperature in Fahrenheit and returns the corresponding number of degrees Kelvin. (For example, 32 degrees Fahrenheit is the same as 273 degrees Kelvin.) Hint: re-use previously-written functions, so you can do it with no numbers in the definition.

• You've just learned that 0 Kelvin is, more accurately, -273.15 Celsius. Make whatever modifications are necessary to accommodate this more-accurate conversion in both c->k and f->k. How much of the program did you need to change?

• Develop a function named convert-3-digits which takes in three numbers (the hundreds, tens, and ones places of a 3-digit number, in that order) and returns the 3-digit number. For example,
  (convert-3-digits 4 2 5)
  should return the number 425. Note that Scheme doesn't have an operation for "put this number next to that one"; you have to use arithmetic operations like +, -, *, /.

  Next, develop a function named convert-3-reversed which takes in the ones, tens, and hundreds places of a 3-digit number, in that order, and returns the 3-digit number. For example,
  (convert-3-reversed 5 7 2)
  should return the number 275. Hint: re-use an old function!

• Do (but don't turn in) all the exercises from section 2.4 of the textbook (the ones about errors).

• Develop a function can-vote? which takes in a person's age and returns a Boolean indicating whether that person is old enough to vote.

• Develop a function can-vote-but-not-drink? which takes in a person's age and returns a Boolean indicating whether that person is old enough to vote, but too young to drink alcohol.

• Develop a function salutation which takes in an hour of the day (a number in the range 1-24) and returns one of the three strings "Good morning", "Good afternoon", or "Good evening" as appropriate. (Let's say that afternoon is any time from 12 to 5 inclusive.)

• Develop a function reply which takes in one of the three strings "Good morning", "Good afternoon", or "Good evening", and returns one of the three strings "Not until I've had my coffee", "I need a nap", or "When is dinner?" respectively. If the input is a string other than the three specified, the answer should be "Huh?".

Grading standards

Pre-term Survey:         /5
(I'm not grading on what you say, only on whether you filled it out.)

"Daily" Survey:         /5
(Ditto.)

Essay:         /30
(Grading primarily on content: convince me that you've read some of the adages and thought about them.)

Error log:       /20
(I'm not grading on how many or how few errors you encountered, only on whether you recorded them adequately.)

General skills:

Total:         /465