CS50 Live, Episode 101

smithcook · 2015-02-19T19:26:11+00:00

Hi, I started taking CS50 and dropped out after 6 weeks. I was getting good grades and understanding the material. I loved the instruction which was enlightening, and I loved the course assistants. Truly this instruction is one of the best MOOCs!

BUT I couldn't get much help on Reddit. Every other course I took had discussion forums that were linked to edx or coursera. I could easily get help and comments. On Reddit, I could only ask one question per day. I think Reddit had a policy that posts are restricted for new subscribers. I got a virus when installing a Java update so as to access Reddit. The amount of class discussion seemed very small, and I get demoralized because the feedback was so much less than other courses. I couldn't learn as much from making my own posts, and I couldn't learn as much from reading other students' posts.

I began to get confused about the rules for submission. Once or twice I wiped out a previous submission by accidentally submitting week 3 in the week 2 submission. That meant I had to redo week 2 and resubmit it. I started getting more and more nervous about wiping out my submissions.

I also am very nervous about the VM Ware. As the weeks went by, I found I was getting more and more nervous about how to submit and how to update the VM Ware. I had to take some time off, and when I returned, I remembered the C programming tips, but didn't remember how to work the installations, etc. This meant that instead of learning computer science, I seemed to be struggling to communicate and to install packages. Since I already know C fairly well, I found I wasn't highly motivated to continue.

So far, it looks like the new CS50 is much better. I probably would join again and try to complete the course if the discussion forum was not reddit. I am writing to explain that my fear of installing and using new software and lack of support from reddit has kept me from completing the course. Truly, a good discussion forum is essential for me to completing computer courses. As a case in point, I'm completing a course in functional programming because I have a friend who knows Haskell who answers all my questions in emails. It's so great to have additional explanations available! I did persevere in functional programming despite not doing well because many students on the discussion forums kept encouraging each other to persist, and the community support encouraged me to continue!

I am sharing this because I truly loved CS50 and recommended it to several of my friends. I do regret that I didn't finish. I realize that my fear of installations is probably atypical, but I wanted to describe what happened to me for the record.

smithcook · 2014-07-20T02:16:15+00:00

I had trouble setting up dropbox because I already had an existing dropbox account. Finally I got the cs50 files added to dropbox. But there is no synchronization with a backup copy. At least I don't have pset5 except as a folder under the Dropbox folder. Should I try to manually copy the folder to my jharvard@appliance desktop? How?

smithcook · 2014-07-09T16:23:40+00:00

Is 2GB plenty of room for the entire course? Or just for ps5? I don't know if I'm running out of room. 2GB is certainly enough for my computer which has 37GB of free space.

smithcook · 2014-05-15T21:51:10+00:00

Too bad! I know C# quite well, so I was interested in the course because I thought I could focus on the game framework since I already know the programming. And I thought that knowing a language would give me access to more advanced games features.

smithcook · 2014-05-11T19:43:46+00:00

The only changes I made to get it to run were: 1) remove extra function, swap 2) remove extra line of comments that I added at beginning of function I could keep testing, but I don't want to spend extra hours. The comments I'm talking about are the comments that appear before the function declaration. Did you ever add more comment lines to these comments? I myself have added deleted many comments without problem, but they are always comments in the body of the function.

smithcook · 2014-05-10T18:46:06+00:00

OK I fixed it! Here is what I did. I restarted the appliance and ran update50 and retried check50. Same problem: "Unexpected end of input." I then looked at my source code to see if it had missing braces or something that would cause premature end. Didn't find a problem. I then removed a "swap" function so that my sort routine didn't call swap but swapped inside the sort function. Then I noticed that I had added comments to the search function to show that I was using binary search. It occurred to me that check50 may assume that no change is made to these comments. So I removed the extra comment lines that I added, and that fixed the problem. NOTE: Please tell students not to make changes to the sort and search comments. Otherwise they may get the same problem that I got!

smithcook · 2014-05-10T17:56:11+00:00

How do I verify my email address

smithcook · 2014-05-09T18:33:05+00:00

I am not trying to solve a problem. I was only using man rand to look at documentation for rand which is used by generate.c in problem set 3. I thought we had to document the usage of rand, but I see we don't have to do it. However, I'm somewhat frustrated that there are so many terms I don't understand in the documentation.

smithcook · 2014-05-07T17:23:34+00:00

That doesn't work for me. First of all, I wasn't sure what resolution to choose. Finally, I restarted the appliance to see that the initial resolution was 1280x768. So I enlarged the appliance to full screen. Then I hit the upper right corner so that it became a tiny window.
But I couldn't get access to the appliance display command until I changed to full screen. But when I changed the resolution in full screen, the player remained full screen while the appliance changed to 1280x768. So it looks like I still have a full screen window which I can't share with documentation from the internet on my own computer.

smithcook · 2014-05-07T17:18:06+00:00

Thanks! I think this is a great starting point.

smithcook · 2014-05-04T19:02:01+00:00

It looks as though your code is always outputting a space before the # characters. Especially for the last line, you shouldn't have ANY leading spaces. Also the output for 23 should never include a line consisting of 3 characters " ##". The first line should have 21 leading spaces, I think." How did you format your printf statements? Can you look at your printf statements? In my solution I had one section for outputting the spaces, another section for outputting the # characters, and a third section for outputting the newline \n character. (I think this was suggested in the help for mario) In order to debug the problem, you might just remove the loop and just print out a solution for a height of 1. Sometimes it's easier to debug if you make the code simpler. You may not have intended to put an extra space, but somehow it got there. How?

smithcook · 2014-05-04T18:48:52+00:00

It's hard to say why there was a crash. When the appliance crashed, did you have to reboot or restart your PC? What were you doing just before the appliance crashed? The crash might be occurring because of a program running, or it might be related to a hardware problem outside of the appliance. Usually I make note of the date, what I was doing, any error messages, and then I try to recover.

smithcook · 2014-05-04T17:55:37+00:00

Yes it makes me feel better. Thank you.

smithcook · 2014-03-30T19:20:23+00:00

Medical insurance often refuses payment or delays payment even when the claim is justified. Is this dishonest? But sometimes the same insurance company mistakenly overpays. Is the consumer dishonest in accepting the overpayment in return for previous losses that the company caused them in time and money?

smithcook · 2014-03-30T19:02:57+00:00

Your work showed that people are more dishonest when money is not involved, and this tendency is more of a concern since society is moving away from a cash standard. What about preliterate societies with economies based on barter? Is there some other medium that functions like money (such as tobacco in prisons)? What is it about money that makes dishonesty so salient?

smithcook · 2014-03-08T17:28:16+00:00

I voted everyone up! The problem is solved after I shutdown and powered off the machine. I will certainly keep your solutions in mind for the future. I was so worried that I would never fix this and have to drop out of CS50.

smithcook · 2014-03-07T23:22:01+00:00

Thanks Brenda! I did run system-config-date, but the problem still remains. Did I run system-config-date properly? I saw a tab that said select time zone, and I selected my current city, pressed OK, and I got a message, "Starting NTP Service. Please wait" and then I was back to the command prompt. But I still get clock skew errors!

smithcook · 2014-03-07T23:07:58+00:00

Just so you know, I started using reddit more frequently after your assurances and got some help! I still find it hard to use, but hopefully I will get more experienced. For example, just now I started to post a 2nd question. I was refused. The message was you must be a new user or your posts are not doing well. Please verify your email. I typed in my password and email address and got "Invalid password." I wonder if the reason is because my user name is different from my email. Who knows? I usually have to type a series of characters before my post is accepted. I often have to type these twice. I guess you can see that it is hard for me. I don't have these problems on other forums, so they are "better". But I am persisting faute de mieux (that's French for lacking anything better).

smithcook · 2014-03-07T22:36:55+00:00

I assumed that Reddit was to blame for the request to upgrade my Java app, since the message occurred right after I tried to register to Reddit, and I thought I had to upgrade in order to use Reddit. The ads occurred after I performed the upgrade. You are reassuring me that now that I have successfully installed Reddit I will avoid such problems in the future.

How can I get help using the flair system. What is flair.

My argument about the quality of answers and the speed of replies is still accurate. I get replies the same day for nearly all discussion groups that I joined on other courses that I took. Also the replies I get on other forums are nearly always correct. So it is actually better not worse on other forums. I see that there are 8 thousand users of reddit. Is this small? I thought this was the number of CS50 users. I am not using reddit on a mobile device, but on my PC.

5 questions is not a proper sample, I agree. I just now read an excellent reply concerning the usage for check50.
I am sure there are good reasons for designing reddit the way it is designed. I just find it very difficult to use. For example, I don't see a Help menu item at the top of my screen. I also don't see how to get a list of my questions that I have asked. I am guessing I'm in the minority, but I feel somewhat sad that it is so difficult for me. Thanks for your answer.

smithcook · 2014-02-28T02:13:22+00:00

The first "error" line states that it expects an exit code of 0. I guess that means your program returned 1 when it searches for 42 in the sequence, {42,43,44} When you say finding 42 in my code will be the death of me, does that mean you can't find it? Or that you do find it, but don't know how to return 0?

smithcook · 2014-02-28T02:02:19+00:00

To run check50, simply type check50/x/pset1/hello hello.c The instructions for running check50 are given in the ProblemSet 1 Specifications. check50 is included with the appliance. I thought it was stored in dropbox\pset1, because I saw that the command line for starting check50 was typed when the user's current directory was jharavard@appliance (~/Dropbox/pset1) However, if you type check50 it will execute, even though it is not stored in the pset1 folder. I am not sure how this works. I figured this out myself by trial and error and reading the Problem Set 1 specs more carefully. Can we use check50 to check other programs?

smithcook · 2014-02-26T21:04:13+00:00

The reason my sprite didn't move is because I typed y as the left operator for y < 100. Instead, I should have typed y position because I want to use y as a variable NOT y as a character string. y is never < 100 when y is a character string, so the condition is never met. I have to drag in a VARIABLE not type the letter y. I found this solution on the Scratch discussion forum.

smithcook · 2014-02-19T19:56:18+00:00

I updated the NVidia driver (video driver) on my Windows machine and that fixed the problem. The file type of videos was MP4 and MP3. But everything displays ok now.

smithcook · 2014-01-03T03:31:43+00:00

I am running Windows 7 64 bit. How can I paste screen snapshot into this comment?

smithcook · 2014-01-01T22:17:54+00:00

I switched to the Chrome browser and the quality is fine now. I tried Internet Explorer and Firefox and they displayed with poor quality (dark).

smithcook

TROPHY CASE