Date: Tue, 10 Dec 1996 16:51:22 GMT Server: NCSA/1.4.2 Content-type: text/html Last-modified: Sat, 07 Dec 1996 00:41:32 GMT Content-length: 32694 CSE/ENGR 142 Class Messages

CSE/ENGR 142 Class Messages

Autumn 1996

Welcome to CSE/ENGR 142. We will use this page to make all sorts of announcements about the class, homework corrections and clarifications, etc. The newest messages are listed first. Check here often!


12/6/96

Old homework (through HW5) and the midterm exam should be picked up from your TA as soon as possible if you haven't done so already. We will not entertain questions on old homework grading after classes end December 11 (it's already too late for midterm questions). We'll announce later how we'll get HW6 back to you (it may be at the final exam).

Audio in the IPL! Most of you have probably noticed the "Lecture Slides with Audio" link on our main page, and some of you report having used it at home. Viewing the slides while listening to the complete recorded lectures from last quarter might strike you as a fabulous and painless way to study for the final exam. We now have audio capability in the IPL. You can bring your own headset (an ordinary Walkman-type headset should work) and ask the lab monitor exactly where to plug it in. The Macs and some of the PCs in Suzallo Library are audio-ready, too. If you want to listen at home, there's complete information on the audio page about what is needed. Enjoy!

12/5/96

Section Q in the course packet ("Libraries, File I/O") is incomplete; only one of the three original pages was reproduced. Sorry. The missing pages can be found on the Web. (Actually, it's likely we won't cover all of this material, anyway).

Holiday Hours in the IPL. The IPL will remain open normal hours through December 16. December 17 and 18 it may be partially closed for cleaning; after that it will close and not reopen until Monday, January 6. Consultants will be on full duty until 5:00 on Monday, December 9.

12/4/96

Computing survey results have been tabulated for the 145 people who have responded so far. Some of the comments are pretty fascinating (look for the one about "eating oreos and drinking wine" as an advantage of computing at home). If you haven't taken the survey yet, we would really like you to -- why not take it now, before reading your fellow students' responses, to keep from being influenced by them.

11/27/96

Thanksgiving holiday hours for the IPL: closing at 5:00 pm Wednesday; closed all day Thursday and Friday; open 9-5 Saturday, noon-midnight Sunday. Consultants may not be working their regularly scheduled hours.

A copy of the problems from the recent ACM regional programming contest has been thumbtacked to the bulletin board outside the IPL. If you borrow it to study or copy, please return it promptly. So far, that particular problem set doesn't seem to be on-line anywhere. You can look at lots of problems from previous competitions on the ACM contest archive page. Practically all of them are solvable (in principle) with what you now know about C programming, except that they take their input from a file rather than from the keyboard.

11/26/96

There's been a problem printing hw6orig.c from within MSVC -- the printing is cut off after about two pages. You can use another program to print from (such as Notepad), or bring up the "direct" copy of hw6orig.c from the HW6 page and print from Netscape. We're looking at the problem and will post a new archive if we can find a solution. Sorry once again for any inconvenience.

11/26/96

The PC archive for HW6 has been reenabled. The McAfee virus checker found no infection. Nevertheless, use caution as always when transferring files from one computer to another. If you have virus checking software on your home computer (strongly recommended anyway), you might wish to run it against your hard drive before and after loading and unpacking the HW6 archive. Please report any problems right away. And we are very sorry for the inconvenience.

The PC archive has been temporarily disabled due to suspicion of a virus. We hope to have it back shortly. Meanwhile, remember that you can study the hw6orig.c program and the detailed instructions to help develop your design specification. The only thing you can't do is run the demo.

11/26/96

Two of the comments in the HW6orig.c program are reversed. In the function draw_world(), where it says /* draw horizontal grid lines */ it should say /* draw vertical grid lines */ and vice-versa.

11/25/96

Please help us by filling out a questionnaire on computing support. We would like to find out what we can do over the next quarter or so to improve computing support for this course, both for those using the programming lab and for those computing at home. The form is easy and fun to fill out and submit, so please do it now, or find a few minutes to do so sometime in the next few days.

11/25/96

As we announced in class this morning, the UW teams did spectacularly well in the ACM programming competition on Saturday. Thanks go to all of you for tolerating the loss of the IPL for the day. A special thanks to a couple of students in the course who worked as volunteers at the event. You can find their names, and lots more interesting information, at http://www.cs.washington.edu/homes/lazowska/acm/.

11/22/96

HW#6 is now available on the Web. Note that a piece of it is due next Wednesday, November 27 (the date on the in-class handout, November 21, was obviously wrong).

11/20/96

Clarification on HW#5: A comment buried in the code of HW5orig.c suggests that the user should be able to press 0-9 on the keyboard in order to change the message number. Please ignore this comment; it was left over from an early version of the demo program. You do not have provide this functionality in your program. If you've already done so, it's OK to leave it in, however. Apologies for any confusion.

11/19/96

HW#5 and Windows 3.1: In case you're running Windows 3.1 at home, we have a 16-bit executable version of the demo which can be downloaded. However, it will probably run only if you have Borland C++ installed. If you're using Windows 95 or Windows NT, please don't even bother; if you are on Windows 3.1, try it out and let us know if you encounter any problems.

11/19/96

More statistics from the midterm exam. 424 students took the test. Perfect score was 72. Standard deviation was 12.7. There were 6 72's (100%) and 12 71's. 112 students scored 65 (90%) or above. The mean was 55.2 (77%). The median was 59 (82%); 210 students were below the median and 206 were above. There were 74 scores below 44 (60%).

11/18/96

The IPL will be unavailable on Saturday, November 23. It will probably also be unavailable for the final hour of normal open times on Friday, Nov. 22, i.e., unavailable from 5:00pm to 6:00pm. This is because the IPL will be the venue for the ACM Programming Competition. If you're interesting in volunteering to help out with the competition, talk to one of the instructors or to professor Dan Weld (weld@cs.washington.edu). It would be a great way to meet students from other universities who are also interesting in computing. Other campus computing sites should be open normal hours on those days.

HW#5 is now open for turn-in. Some changes have been made to the software which we hope will result in overall faster processing. If you notice any problems at all, please notify a consultant right away or send e-mail to an instructor.

11/12/96

Fallout from the HW#4 turn-in debacle: Over 350 people bravely overcame the obstacles and got HW#4 turned in by early Saturday afternoon. We're sorry it was such a frustrating experience. We've heard from a couple of people who because of holiday plans had to leave campus before being able to do a successful turn-in. If that was your situation, please send us a short e-mail to that effect (it does not have to have a lengthy justification, just a note as to your name, section, student number, and a brief reason) and we will set up a special period when turnin for HW#4 will be open again. Meantime, the consultants will be asked not to give any further help on HW#4. If you had already sent us e-mail about the situation, please respond again anyway so that we're sure your name will appear on the list of authorized people.

11/9/96

Notes on HW#5: GP142 is a Windows program; it requires a GUI (graphical user interface) environment, and will not run under DOS. It should be OK on Macintosh, although we have not completed our testing there. The demo program currently in the archive will run on Windows 95 or Windows NT only.

We are testing a Windows 3.1 version of the demo and will put that in the archive later; it might require some further set-up or helper files. Meanwhile, if you have Windows 3.1 at home, the hw5orig.c program will probably compile, but we're not sure if it will run properly unless you happen to have the Borland C++ version 4.5 compiler installed; in any case, you will need to figure out how to create a project file or make file that pulls together all the required files.

The turn-in form for HW#5 will not be enabled until all the dust has cleared from HW#4.

11/8/96

A further reminder about the HW#4 lab report: please be sure it is in plain ASCII format (see message from 11/6 below.) There is increasing suspicion that files in .doc or other word processing formats may contribute to the slowdown problem. They are also apparently one cause of the "document has no data" error from Netscape.

Homework #4 deadline has been extended to noon, Saturday November 9; there will be no late penalty for work received by that time. Please put the turn-in receipts, stapled, in an envelope with your name and section on the outside, in the wooden box outside Sieg 128. If you complete turn-in off-campus but are unable to get back to campus to give us the form, please bring it on Tuesday.

We experienced several periods of web server outages or slowdowns on Friday. It may be that the large number of people trying simultaneously to turn in contributed to the problem -- investigation continues. The IPL closes at 6:30 pm on Friday and is supposed to open at 8:30 am Saturday. You can also use Netscape at Suzallo or at the ACC lab (Brooklyn & Pacific, open 24 hours a day). ACC has the Microsoft compiler installed but Suzallo does not. Some students printed copies of their programs and lab reports and put those in the box; you still need to do the electronic turn-in and give us the printed turn-in receipt.

Work turned in electronically after noon on Saturday will not be accepted (unless further network problems necessitate a further deadline extension, which would be announced on the Web.) It's been a frustrating time for many of you; we appreciate your patience.

11/8/96

Sample solutions (.c files) for homeworks 2 and 3 are on the Web, reachable from the corresponding homework pages.

Tabulations are not complete, but it appears the midterm exam average score was about 55 (out of 72), with a standard deviation of about 13.

11/7/96

Mac users have reported that the demo program does not behave as described in situation of lab report question #3. As noted a few days ago, we already know there are differences between Windows 3.1 and Windows 95 versions of the demo in this area. If you are using Macintosh or other platforms, differences are possible. Treat the lab report the way you would a report in an experimental science like biology or chemistry. That is, report what you actually observed; if it's not what you expected, then give a little background or context (such as the platform you are running on, etc.) for the benefit of anyone reading your report.

11/6/96

Turn-in problems. A number of people have reported problems with turn-in. (A typical symptom is a "Document contains no data" error.) In the cases diagnosed so far, the problem turned out to be caused by sending a Microsoft Word format (.doc file) as the lab report. Instead, please send a plain ASCII file(text file). Try the following -

1. hit "save as" in the file menu of Word

2. Change the file type to plain text.

3. save - you should have a plain ASCII file.

4. Turn in that file.

The midterm exam (with and without answers) is now available. There were 72 points possible. We'll try to have some statistics for you by Friday.

More about IPL hours: beginning this Sunday (November 10), the IPL will open at noon on Sundays rather than at 11:00 am.

11/5/96

The HW4 crunch is coming. The number of people who have turned in HW4 is running way behind the number who had HW3 finished at this point before the deadline. That means the IPL is going to be super crowded between now and Friday. "All the computers were busy" or "My computer had a problem that even the consultant couldn't solve" will not be accepted as an excuse for a late turn-in. So get in there now and avoid the last-minute panic.

Veterans' Day Holiday IPL hours. We expect that the IPL will be open normal hours this weekend and on Monday (Veterans' Day), November 11. However, there may be limited technical and consultant support.

10/30/96

If you are in section AA (Brown) or BE (Hong) only: To relieve the crowding in our regular classroom, we have a small overflow room for each exam period on Friday. It is large enough to hold only the students in one section. If you are in section AA: report directly to Sieg 225 for the 9:30 exam. If you are in section BE: report directly to MEB 248 (Mechanical Engineering) for the 11:30 exam. (If this is a hardship for any reason, you can come to the regular room.)

Regardless of your section: when you come to the exam, please know your section number and your student ID number; also please carry your ID card with you. Also, please be on time; we won't be able to give extra time to people who arrive late.

10/29/96

A new HW#4 PC archive is on the Web, and a new version of the detailed instructions. Here's what's different. We found on some systems, the demo program looped, and not on others. The archive now has two executable demos, called demo16.exe (for DOS and Windows 3.1), and demo32.exe (for Windows 95 and Windows NT). For most of your investigations, either version, or the original demo program called hw4demo.exe, will be the same. But for lab report question #3, on the the demo32.exe version exhibits the infinite loop behavior. So please use that version when you come to question #3. Otherwise, everything is the same. Thanks to several early-bird students for discovering this problem.

10/29/96

HW#4 lab report -- question #3. A couple of people have reported that the demo program does NOT loop forever under the conditions described in question #3. We're looking at this, and right now we think it might be because the .exe was created for Windows 3.1, whereas our own test version of it was compiled for Win95. In any case: for now, please ignore question #3; we'll come back to it another time. Question #4, on the other hand, should be OK to proceed with; please note that it refers to hw4orig.c, not the demo program.

10/29/96

Thanks for the comments on Homework #3. We read these comments separated from the rest of the turn-in form, so they are effectively anonymous. Naturally, we could find out who wrote what, but normally don't. So that means if you have a question that you want answered individually, as opposed to just a comment, please send it as an e-mail or talk to us in office hours; or you could include your e-mail address in the comment. In any case, the comments are really valuable to give a sense of how we are doing as well what some of your individual experiences and concerns are. Thanks for taking the time and trouble to type them in.

10/29/96

All of the tips that we have mentioned before have been collected into a single tips page. You can get to it from here or from the main Web page. In addition to previously announced tips on MSVC, there are some new tips for Macintosh users.

10/28/96 (2:00 pm)

The complete HW#4 archive (for PCs) is now on the Web. It is expected that the turn-in form for HW#4 will be enabled later today, shortly after turn-in for HW#3 is closed. Nevertheless, we encourage you to spend considerable time analyzing HW#4 before starting to program.

10/28/96

HW#4 instructions and a skeletal .c program are now available on the Web.

10/24/96

Is the 3-letter redisplay required? Yes. A couple of you have pointed out that this enhancement was not listed as such in the Detailed Instructions. But it was mentioned in a comment in the program. So please go ahead and include it. What is the purpose of it (aside from getting you to reuse some functions)? The customer might have made several errors while typing in the letters. The redisplay serves as a reminder and summary of what has been ordered.

10/23/96

Vertical or horizontal? One of the enhancements in HW#3 is to redisplay the three letters chosen. There isn't any way, using what we've studied so far, that you could display the three letters horizontally across the screen. So they have to be displayed vertically. On the other hand, you can and should find some (simple) way to keep them from immediately disappearing off the top of the screen.

Reminder: Midterm exam is Friday, November 1. A study guide is now on the Web.

10/20/96

An error in a comment in the hw3orig.c program has been pointed out. The function "sales-slip" has the comment /*No calculations should be needed here, only printf's.*/ It turns out you do need to do one simple calculation (which could in fact be embedded in a printf). In any case, don't repeat any calculations which have already been made.

HW#3 is now open for turn-in.

Another tips file on working with workspaces in MSVC++ is now available. If you have trouble with your disk filling up, or get mysterious messages about needing a workspace or about files not being in a workspace, take a few minutes and read through this file. It may or may not solve your immediate problem, but should give you some additional background for understanding the situation.

10/18/96

HW#3 is now available. Locate it via the Homework page from the course homepage.

A sample solution for HW#2 will be posted (on the HW#2 page) within a couple of days.

10/16/96

There are some new tips about one method to keep your floppy disk from filling up. In general, the more you know about MSVC and about Windows 95, the more ways you can discover for yourself about ways to avoid problems like this. Meantime, read this and the previous tips as well.

The quote from today's lecture: "As soon as we started programming, we found to our surprise that it wasn't as easy to get programs right as we had thought. Debugging had to be discovered. I can remember the exact instant when I realized that a large part of my life from then on was going to be spent in finding mistakes in my own programs." Maurice Wilkes, British computer pioneer, 1949; quoted in Expert C Programming: Deep C Secrets by Peter van der Linden (Prentice Hall, 1994), p.109.

10/14/96

HW#2 turn-in form is now available on the Web. The Mac version of HW#2 is now available to download. Please report any problems with either via e-mail.

As mentioned below (10/11/96), you are likely to fill up your diskette once you have created and run hw2b.c and hw2c.c. Aside from starting with a blank high-density disk (single density is definitely too small - ask for help if you are not sure if your disk is formatted at the correct density), there are some techniques for avoiding the problem. One is to copy your .c files to a directory on the hard drive, and create a default project there. The Windows Explorer can be used to create directories and copy files. If you do this, be sure to copy your updated .c files back to the floppy for safekeeping before restarting your computer; all changes to the hard drive are automatically erased when the machine restarts! We will try to post some details on these suggestions later.

A different approach to the problem is to do what the .mdp and .mak files provided on the archive do: they have settings which instruct MSVC to place all the intermediate files on a temporary directory on the hard drive, while allowing your .c file to stay on the floppy. You could do this yourself by adjusting the Settings on the Build menu. In any case, all the intermediate files (.ilk, .pdb and many others) can safely be deleted from your floppy; they are automatically rebuilt when needed.

How closely does your HW#2 solution have to follow the samples? Well, your version should always give a correct answer on valid, reasonable data. But if the input data types are wrong (for example, typing a character when an integer is expected), then the sample is not guaranteed to run correctly, and your program doesn't need to, either. If the data type is right, but the values are unexpected, then both programs should be able to handle it, and in pretty much the same way. The exact wording of output is not crucial as long as it is correct and appropriate. If you find cases where our program seems to be wrong, please send mail with particulars (i.e., give us the exact input values that produce the bad answers.) If you're sure our program is not right for a particular case, then you don't have to make yours do the same wrong thing.

The final "hit any key to terminate the program" or "hit any key to continue" are not essential parts of the solution. They are only there to guarantee that the window stays on the screen so that it can be read. When running from within MSVC they aren't needed, but if you launch the program from the Explorer they may be.

10/11/96

We've put a new version of the HW#2 archive on the Web. If you're happy with the old one, there's no need to load the new one. The new version has so-called "16-bit" executable sample programs. These will run on Windows 3.1 as well as on Windows 95. They look slightly different - the background color is white instead of black, and when the program finishes you have to close the window by clicking on the close "X" in the upper right-hand corner. We also corrected some minor details that various of you had pointed out (thanks - and a commendation for getting started so quickly!) None of these are important as far as how your program works and how it's graded. What counts is getting the right answers for good data and the right behavior for bad data.

10/11/96

With Homework #2, there are some situations that can lead to your A: disk being filled up. For one thing, using a fresh diskette will help. Also, when working on hw2a.c, open the project by double-clicking the .mdp file (as the instructions suggest), not the .c file. We'll try to assemble some other tips for dealing with this.

10/11/96

The Homework #2 assignment is ready now. You can find it on the Web. The distribution includes a couple of sample solutions, in executable (.EXE) form. These exe's will run only on Windows 95 or Windows 95; they won't run on Windows 3.1.

Homework #1 is due today! You must have completed electronic turn-in by 3:30. You must also turn in a (physical) copy of your "receipt," stapled if it is more than one sheet. If you haven't given it to your TA already, please bring it to class today, or drop it in the box across the hall from Sieg 127.

Some brand-new tips on using MSVC and the debugger are available. These were passed out during some of the tutorials and were also distributed in class on Oct. 9.

10/9/96

Some students have asked where the MSVC "tips" are. They are not in MSVC, but rather are files we created and posted on the course Web. You can find the tips from the 142 home page.

10/8/96

Don't forget there will be tutorials today (Tuesday) and Wednesday. Subject is MSVC.

10/7/96

The turn-in form for HW#1 is now ready to use. If you notice problems, please let someone on the staff know as soon as possible.

Dr. Ladner will not hold office hours this Thursday (Oct. 10). You can still reach him via e-mail.

The IPL schedule this week is still a little up in the air. We hope it will be open during the hours posted in the lab information page, but in case it's not, please leave room for recovery, that is, don't leave the homework until the last day. Do it now if you haven't already.

10/4/96

The turn-in form for HW#1 has not been enabled yet. Apparently a number of you have already reached that point in the homework - that's great! We'll have the turn-in form enabled early next week (it will be announced here, or check the HW#1 page).

10/3/96

Homework #1 is now on the Web. To do it, you'll need some time and lots of patience (and a little magic). It's due on Friday, October 11. Get started today! There will be tutorials next week on Tuesday and Wednesday, but don't wait until then.

10/2/96

Compiler discount. We have the final word on getting a further discounted version of MSVC++ 4.2, and the news is not good. We were not able to work out a special arrangment with Microsoft, other than what is already available in the bookstore: MSVC++ 4.0 at about $55.00 plus tax. (This is actually way cheaper than the official "street price" of the product).

Tutorials: At present, no more are scheduled for this week. There should be several next Wednesday; keep checking the tutorials and special demos page.

Lab hours: Some tentative hours for this week are Thursday 9-6; Fri 9-5, Sat 9-6; Sun 11-9. Also check the lab information page.

10/1/96

A new page has been set up with information about tutorials and special demos. Several more are planned for this week and next.

Instructor office hours corrections and change. The office hours for Dickey & Ladner were switched on the original printed Syllabus handout. Dickey has also made a change in Friday office hours. Apologies to anyone who may have stopped by and not found one of us in our office at the announced times. The corrected times are now on the Syllabus page and on the Staff page. For reference, here they are again: Dickey: M & W, 1:30-2:30; F 2:30-3:30. Ladner: Tu & Th 10:30am-noon. TA times will be posted later this week on the Staff page.

9/30/96
9/23/96

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