Other people might choose not to answer, as the question has already been answered, and it might offend the person who commented with the answer. In time, this will lead to the site having a lot of questions with 0 answers which actually have an answer in the comments.

1) Potentially waste time of people. Personally speaking, I read the question before reading the comments, and so I have just wasted a few minutes when I possibly didn't have to. Some people might choose to answer it straight away and find that they have just repeated someone's comment in an answer.

2) The question goes to the unanswered list and they are bumped up periodically by the Community user.

3) Comments are not indexed by the full text search. So we have valuable content just lying around in dead questions.

Here are a couple of examples:

If $f$ continuous and $f(x^2) = f(x)$, then $f$ is a const. This one has an incorrect answer, while the correct answer is in a comment.. The commenter was kind enough to add a detailed answer, upon request.

Connectedness of sets in the plane with rational coordinates and at least one irrational

This problem seems to be more severe with homework like questions. If one is worried about earning trivial rep, one call always add an answer and mark it CW.

So, in case someone adds an answer in comments, what should one do (while not hurting any feelings perhaps)? (Ignore is not an option :-))

I wanted to open this, so we could direct any future comment-answerers to what the community opinion is regarding this (if any).

Note: I am not suggesting we have a policy/faq entry. This question would serve that purpose, if possible.

• Here's a related question: meta.math.stackexchange.com/questions/1148/…. In that case it was the asker whose question was answered in the comments not wanting the question to remain "Unanswered", and the accepted advice was for the asker to post a CW answer. – Jonas Meyer Jan 27 '11 at 22:43
• In this case, a simple request to Sivaram produced an answer post. – Arturo Magidin Jan 28 '11 at 17:05
• Actually, I think this is somewhat of a balancing act. For instance, sometimes a learning student might ask a question, where it would in fact be more appropriate to give a hint instead. At other times, the OP may find a comment useful and will ask the commenter to make the comment into an answer which the OP is willing to accept (for example: math.stackexchange.com/questions/107731/limit-points-of-sinn/…). In general, where a hint is more appropriate, I think one should comment rather than answer. – user2093 Mar 13 '12 at 4:46
• @WNY: You can always edit your answers (which can start out as hints). They are not set in stone. By adding an answer you let other folks know that you are willing to provide guidance to OP and closure to the question. If you just comment, no one has any clue whether you are going to follow up etc and might lead to the question having no answers. – Aryabhata Mar 13 '12 at 5:28
• This annoys me to no end, people just posting their answer as a comment instead of an answer. A problem that I'd add is that it comes across as an attempt to have their answer be the first thing people see after reading the question, without having to go through the voting process. I guess people do it because they think their answer is too short or something, but it's still annoying. – Kyle Delaney Nov 23 '15 at 3:36
• I'm a prime offender for this. I'm aware that other SE sites strongly discourage answers in comments, but I see one difference on MSE; often a hint can lead the OP to find the answer themselves (and they will get more out of it). Is it acceptable to write a hint as an answer? I couldn't find any clarification in the help center. – stewbasic Apr 20 '17 at 3:08
• @stewbasic: If you are willing to followup and edit to make it a complete answer later, posting a hint-answer should not be a problem... – Aryabhata Apr 20 '17 at 22:20

I think one should first leave a comment asking the user to post their comment as an answer, explaining that this will allow the question to be marked as answered. This often works, and it may encourage the user to post full answers in the future.

If the commenter won't do so, I agree that one should go ahead and post the comment as a community wiki answer. (As of writing, 10 other people agree that this is a good idea, going by the votes on this previous question).

On the other hand, if one wants to add further information and not merely duplicate the content of someone else's comment, there is nothing wrong with posting that as one's own (i.e. not CW) answer. If one is concerned about hurting feelings, one can acknowledge in the beginning that this answer is an elaboration of the answer given by the other user in the comments.

• What if one decides to expand a bit on the answer? Especially if it is a new user, they might need the rep to gain certain privileges. Marking it as CW probably won't help in that regard. – Aryabhata Jan 27 '11 at 23:09
• @Moron: I edited my answer to the effect that if you are adding your own contribution, it should be OK to make that a non-CW answer. (I thought I should put that in the answer so people can vote it up or down appropriately, while one can't vote down a comment.) – Rahul Jan 27 '11 at 23:40
• answers posted as as comments are fair game to be reposted as true answers. If users continue to post answers as comments over time, I would consider that a somewhat abusive use of the system. – Jeff Atwood Jan 28 '11 at 1:28
• I am posting community wikis for questions resolved in the comments as recommended in this article, but I am receiving reputation points when people upvote them, which seems unfair, since I really didn't do anything (often it is my question being answered)! – Eric Auld Jul 28 '13 at 15:20
• @EricAuld That can't happen, if the post is CW. Possible explanation: after you posted CW answer to your question, more users saw it and upvoted the question along with the answer. In the reputation report, it's not easy to tell what brought you points: question or its answer. – Post No Bulls Dec 16 '13 at 2:51
• Would it be a faux pas to ask people to post their comments as answers if it's someone else's question and not your own? – Kyle Delaney Nov 23 '15 at 3:38
• @Kyle: Not at all, people do that all the time. Heck, people often just repost other people's comments as answers too, so you could just do that and cut out the middleman. (As you can tell, in the ~5 years since I wrote that answer my opinion has become much less conservative.) – Rahul Nov 23 '15 at 4:00