The 2 links to reference.cs50.net (in the Getting Ready) section currently show:

https://reference.cs50.net/stdlib.h/srand48 and
https://reference.cs50.net/stdlib.h/drand48

These should be:

https://reference.cs50.net/stdlib/srand48
https://reference.cs50.net/stdlib/drand48

(without the .h in the folder name)

From here:
http://docs.cs50.net/2016/x/ap/problems/rng/rng.html

(reported by a student)

re: SPELLER problem:

You may add functions to dictionary.c or to files of your own creation so long as all of your code compiles via make.

If a student does create these files and creates their own Makefile, they might figure out that check50 can still run by including those extra files as part of the command line args. But, submit50 does not allow them to submit any additional files, so the grading will fail.

Files that will be submitted:
Makefile
dictionary.c
dictionary.h
questions.txt
speller.c

Should we be advising students not to use extra files instead?

In the caesar and vigenere problem docs, I see:

\[c_i = (p_i + k_j) \bmod 26\]

rather than a formatted version.

I also notice in my console that I get
/extensions/MathMenu.js?V=2.7.1
Failed to load resource: the server responded with a status of 404 (Not Found)
/extensions/MathZoom.js?V=2.7.1
Failed to load resource: the server responded with a status of 404

Not sure if that's related.

From the course page: https://courses.edx.org/courses/course-v1:HarvardX+CS50+AP/course/ the links for FAQs, Instructions, Progress, and Syllabus all refer to a 2017 deadline. @Erin-c

"Also display the user’s current cash balance along with a grand total (i.e., stocks' total value plus cash)." under Index

Staff solution doesn't have the grand total.

Hello guys!

I was trying to access a link referred by whodunit at problem set 4.

It happens that the link is returning a 400 bad request response, and with it, leaking some information about the webserver.

I also tried to issue the request via command line HTTP client and also had the same result.

I hope you guys fix the docs if the link doesn't exist or fix it, so people in the future doesn't get frustrated or so.

I also recommend you to remove the server HTTP header response.

See you guys out there!

Hi there! I'm a new student, and when I went to follow the instructions to make sure Flash was enabled in Chrome, I got a bit confused. I think the instructions as they are in the problem set are a bit out of date: https://docs.cs50.net/2018/x/psets/0/pset0.html#tldr

Right now it reads:
"Make sure that your web browser has Flash enabled. If you’re using Google Chrome, you can go to chrome://settings/content, click on Advanced → Content settings, and make sure you "allow" Flash!"

To make this more clear to future students with less experience (like me!) I'd suggest revising to:
"Make sure that your web browser has Flash enabled. If you're using Google Chrome, you can type chrome://settings/content in your browser, then scroll down to the "Flash" section. Make sure "Ask First" is enabled so you can allow Flash to run when you're using Scratch."

Thank you!
Kimberlee

In the advice section in pset2, there's a sentence going like this:

For instance, if trying to compile hello, and
make readability
is yielding errors, try running
help50 make readability
instead!

The word "hello" on the first line should be changed to "readability".

It says

In ASCII, the letter A is the decimal number 65, B 66, C 77, and so on.

C should be 67

In the Find problem, this paragraph no longer fully applies:

The first line tells make that the "target" called generate should be built by invoking the second line’s command. Moreover, that first line tells make that generate is dependent on generate.c, the implication of which is that make will only re-build generate on subsequent runs if that file was modified since make last built generate. Neat time-saving trick, eh? In fact, go ahead and execute the command below again, assuming you haven’t modified generate.c.

 make generate

You should be informed that generate is already up-to-date.

(note that this also applies to the https://cdn.cs50.net/2016/x/psets/3/pset3/pset3.html spec, and has raised questions from edX students).

Link to notes: https://cs50.harvard.edu/x/2021/notes/9/#post

In the POST method documentation, the method used inside form tag is mentioned as "form". There is no such method for form tag.

During lecture(video), Prof. Malan used <form action="/greet" method="post"> for demonstrating usage of POST method

I have watched the "Week 1 : C" and am doing the Pset1.

• problems/credit.adoc#L109 (or alternatively ~/psets/1/credit) says "... time to debug!"
• but debugging is not covered in the course so far.
• is this ommission intentional?
• any suggested resource for learning how to debug?

Per #6, YouTube embeds are now responsive with new default layout.

A few notes:

• The 'Personalize Google News' instruction is now done via 'Manage sections'
• URL syntax had been changed and looks simpler now unlike this example link in the documentation:
  https://news.google.com/news/section?cf=all&pz=1&geo=Cambridge,+Massachusetts&ned=us&redirect=true
• Parameters like cf, pz, and redirect are no more, like this:
  https://news.google.com/news/local/section/geo/Cambridge,%20Massachusetts?ned=us&hl=en
• Also the URL for the RSS is changed, like this:
  https://news.google.com/news/rss/local/section/geo/Cambridge,%20Massachusetts?ned=us&hl=en

e.g. × or × to render the multiplication cross symbol no longer works, and I imagine also that other HTML entities may no longer work as well?

For the Whodunit problem, you are asked: "In questions.txt, answer each of the following questions in a sentence or more."

Folks are asking where questions.txt is. I've been telling them to create it themselves and save it in their whodunit folder (which I thought might be obvious, but perhaps we should add a line of instruction saying this?)

When we debut the new check50 and integrate it with CS50.me, we'll need to...

For pset6, replace the submit50 slug cs50/2017/x/pset6 with:

• C-to-Python slugs:
  • cs50/2017/x/python/mario/less
  • cs50/2017/x/python/mario/more
  • cs50/2017/x/python/greedy
  • cs50/2017/x/python/credit
  • cs50/2017/x/python/caesar
  • cs50/2017/x/python/vigenere
  • cs50/2017/x/python/crack
• Sentiments slugs:
  • cs50/2017/x/smile
  • cs50/2017/x/tweets
  • cs50/2017/x/sentiments

For pset0, if we're going to have students submit via GitHub:

• instructions for creating a cs50/2017/x/scratch branch, and uploading their .sb file.

For all psets:

• mandate the cs50/ prefix if we're going to get rid of the assumption of cs50/ at the beginning

CC @dmalan @crossroads1112

There are inconsistencies between the submission instructions vs subfolder creation instructions on the edX pset1.

Summary:
On pset1.html, it requests that students create the C files under ~/workspace/pset1 folder. However, the instructions on specific assignments, such as hello.html states that students should create a pset1/hello/ subfolder while instructions on other assignments such as water.html states that the C file should be created under the pset1/ folder. Unfortunately this causes some of the submission instructions on the pset1.html page to be incorrect.

The following submission instructions could use update to reflect the instructions on each assignment:

• hello.html instructs students to create folder pset1/hello/. If true, the submission instruction for hello on pset1.html should be updated to cd ~/workspace/pset1/hello/.

• less/mario.html instructs students to create folder pset1/mario/less/. If true, the submission instruction for less-comfortable version of mario on pset1.html should be updated to cd ~/workspace/pset1/mario/less/.

• more/mario.html instructs students to create folder pset1/more/. If true, the submission instruction for more-comfortable version of mario on pset1.html should be updated to cd ~/workspace/pset1/more/. Additionally, I would like to point out the inconsistency in folder naming between less and more comfortable versions of mario.

• credit.html instructs students to create folder pset1/credit/. If true, the submission instruction for credit on pset1.html should be updated to cd ~/workspace/pset1/credit/.

The following submission instructions work correctly, but the folder creation instructions are inconsistent with the rest of the pset1 assignments:

• water.html does not request for students to create a pset1/water subfolder

• greedy.html does not request for students to create a pset1/greedy subfolder.

docs/_pages/2018/spring/psets/5/speller/speller.adoc

The playlist for the walkthroughs is currently: speller -> check -> load -> unload.

This should probably be: speller -> load -> check -> unload, as "load" contains elaborate info on the data structure that is referenced in check.

In the CS50 Finance problem, following the API URL example with a valid API key leads to an error:

Indeed, IEX lets you download stock quotes via their API (application programming interface) using URLs like https://cloud-sse.iexapis.com/stable/stock/nflx/quote?token=API_KEY.

Looking at the documentation on IEX, the SSE endpoint is only available for paid users. I believe the correct URL should be https://cloud.iexapis.com/stable/stock/nflx/quote?token=API_KEY (cloud-sse -> cloud), which is used in the problem distribution code.

In both the more & less versions of the Find problem, the Usage section simply says:

Your program should behave per the examples below. Assumed that the underlined text is what some user has typed.

$ ./find TODO

Seems there's something missing.

https://docs.cs50.net

Obviously it is not ever linked to, but I imagine this isn't intentional.

• change Open hex to Open as hexadecimal
• change Bytes per offset to Start with byte and its order
• remove the View > Night Mode sentence once theme is fixed

CC @dmalan

https://github.com/cs50/docs/blob/master/_pages/2018/x/psets/6/pset6.adoc

The commands for 'mario' and 'similarities' are missing the /less/ and /more/ on the ends for the change directory commands.

So copy and pasting to terminal doesn't work.

Unfortunately, Yahoo Finance API endpoint http://download.finance.yahoo.com/d/quotes.csv mentioned in https://github.com/cs50/docs/blob/d874daaf91ac96fbc64ae3be39b6d7ce3a59591b/_pages/problems/finance/finance.adoc#background and used by lookup() function in finance/helpers.py of Problem Set 7 is no longer available. download.finance.yahoo.com doesn't even resolve. Here is post by Yahoo support staff member which says:

UPDATE: It has come to our attention that this service is being used in violation of the Yahoo Terms of Service. As such, the service is being discontinued. For all future markets and equities data research, please refer to finance.yahoo.com. Thank you.

On pages like http://docs.cs50.net/problems/fifteen/fifteen.html when there is a $ preceding a command, it would be helpful to format it in a way as to not copy paste the $ .

You could consider an approach like Digital Ocean uses in their tutorials:
https://www.digitalocean.com/community/tutorials/how-to-install-moodle-on-ubuntu-16-04

Alternatively, we could just remove the dollar signs. Other places in the docs are already this way. (See http://docs.cs50.net/2017/x/psets/5/pset5.html for examples).

Unclear how easily MathJax.js can be embedded, though.

https://docs.cs50.net/2018/fall/psets/3/resize/less/resize.html

Zamyla seems to suggest that more video should be included, but there isn't any :-)

In the notes for lecture 4 , chapter string, there is a typo in the second sub-item:

"But it turns out that each character is in stored in memory at a byte with some address, ..."

E.g., _pages/2017/fall/syllabus/cs50.adoc is yielding a title of Cs50 based on its filename.

Is it possible to work and contribute to html projects for cs50 within Github or do I need to download the files to my local drive and work within there? Thanks

sir,
The pset1 mario more for more comfortable people doesn't have a key hint regarding the use of \n.
please, consider the following case
case no:1 : check50 marks this solution incorrect.
height:4
0123456789

• • # # * *\n //new line is printed after 9.

• • ##* *\n

• ###*\n

####\n

case no: 2 : check50 marks this solution correct.
height:4
0123456789

• • • #\n //new line is printed after the right-most hash.

• • ##\n

• ###\n

####\n

Both the solutions are equally correct, I have seen many people on cs50 asking why their solution is incorrect and wasting their time on this silly mistake which is easy to solve when informed.
A hint should be there that you don't have to print spaces after the right-most hash. A \n should be used.
thanks!

sir,
The pset1 mario more for more comfortable people doesn't have a key hint regarding the use of \n.
please, consider the following case
case no:1 : check50 marks this solution incorrect. consider ~ for spaces.

   height:4
   0123456789
   ~~~#~~#~~~\n                // new line is used after the length of row.ie (height*2)+2
   ~~##~~##~~\n
   ~###~~###~\n
   ####~~####\n

case no: 2 : check50 marks this solution correct. consider ~ for spaces.

  height:4
  0123456789
  ~~~#~~#\n                           // New line is used after the rightmost hash!
  ~~##~~##\n
  ~###~~###\n
  ####~~####\n

Both the solutions are equally correct, I have seen many people on cs50 group asking why their solution is incorrect and wasting their time on this silly mistake which is easy to solve when informed.
A hint should be there that you don't have to print spaces after the right-most hash. A \n should be used.
thanks!

The spec explicitly says

But you should ultimately find that the image contains 50 JPEGs.

This leads many students to assume they should hard-code their number of jpgs to 50 and structure their program this way (with a for loop that ends when 50 jpgs are found). This works perfectly fine with the card.raw that is in the distro code, but check50 uses a different raw file (with only 16 files) so their program is then "killed by server" because it never finds the 17th signature and goes into an infinite loop.

Should we add something like:

Note that your program may be tested with a different card image so you should not hard-code that number, but instead, search the entire file for all the JPEGs within it.

https://docs.cs50.net/2019/x/new.html
Problem sets part is copied from what's new in 2018, but isn't valid in 2019.
music now isn't in 2019 psets.

I beg a pardon if this is not apropriate place to ask such questions, but unfortunatelly i can't find more appropriate place to ask it.

In Problem Set 4, Specifications described only 2 error states:

1. Your program should accept exactly one command-line argument, the name of a forensic image from which to recover JPEGs. + If your program is not executed with exactly one command-line argument, it should remind the user of correct usage, as with fprintf (to stderr), and main should return 1.

2. If the forensic image cannot be opened for reading, your program should inform the user as much, as with fprintf (to stderr), and main should return 2.

Aren't we suppose also to return error (let's say with a code 3), in case if program can't create a restored image file. Here is a code i am talking about that cover this missing note

When submitting this problem, you’ll be asked whodunit!

Now that we've removed the step 2 form from the submission, we no longer ask whodunit.

Maybe we should add this to the README.md as the last question? and tell them to come back and answer it once they've found out?

Looks like the "more" hint for the sort part of find was copy/pasted from the "less" hint, as it says to make sure you use an O(n^2) sort method, yet the problem requires a O(n) solution.

A la problems/*. This new layout:

• Embeds YouTube vids responsively so that they resize for mobile.
• Adds support for LaTeX, a la https://github.com/cs50/docs/blame/master/problems/caesar/caesar.adoc#L45.

https://github.com/cs50/docs/blob/master/_layouts/default.html

Aok to make your own for AP too, but I suspect I'll continue tweaking default for a few weeks if you want to wait a bit!

MC has a new BIN range of 222100-272099 in addition to their existing 510000-549999 That will be a bit trickier! https://www.mastercard.us/en-us/issuers/get-support/2-series-bin-expansion.html

Do we need to update the spec / solution / check to handle this new range? Or, perhaps just say "you don't need to handle this range in this problem"?

Seems there are a few minor differences between the code shown in lecture the code shown in the notes for Week 8, pointed out by an online student:

• Lecture code for application.py with froshIMs seems to be a superset of the code shown in lecture, which may be okay in the interest of giving students more info rather than less, but an example is that there's a missing conditional for "captain" in the lecture code, whereas it shows up in notes.
• store.html seems to be omitted from the notes during the shopping cart section.