I have noticed, of late, people providing answers/copious hints to the question in comments instead of actually adding an answer on their own.

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.

Some possible consequences of having answers in 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.

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    $\begingroup$ 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. $\endgroup$ Jan 27, 2011 at 22:43
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    $\begingroup$ In this case, a simple request to Sivaram produced an answer post. $\endgroup$ Jan 28, 2011 at 17:05
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    $\begingroup$ 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. $\endgroup$
    – user2093
    Mar 13, 2012 at 4:46
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    $\begingroup$ @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. $\endgroup$
    – Aryabhata
    Mar 13, 2012 at 5:28
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    $\begingroup$ 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. $\endgroup$ Nov 23, 2015 at 3:36
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    $\begingroup$ 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. $\endgroup$
    – stewbasic
    Apr 20, 2017 at 3:08
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    $\begingroup$ @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... $\endgroup$
    – Aryabhata
    Apr 20, 2017 at 22:20

2 Answers 2


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.

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    $\begingroup$ 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. $\endgroup$
    – Aryabhata
    Jan 27, 2011 at 23:09
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    $\begingroup$ @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.) $\endgroup$
    – user856
    Jan 27, 2011 at 23:40
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    $\begingroup$ 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. $\endgroup$ Jan 28, 2011 at 1:28
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    $\begingroup$ 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)! $\endgroup$
    – Eric Auld
    Jul 28, 2013 at 15:20
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    $\begingroup$ @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. $\endgroup$ Dec 16, 2013 at 2:51
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    $\begingroup$ 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? $\endgroup$ Nov 23, 2015 at 3:38
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    $\begingroup$ @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.) $\endgroup$
    – user856
    Nov 23, 2015 at 4:00

I actually wanted to post the same question since this issue has been bothering me for a long time, but I found this post (and lots of duplicates), so let me just add my 2 cents here.

I think we have a huge problem with people writing answers in comments. My assumption is that sometimes they think their answer is too short to be an answer, even though it is an answer. Even worse, they might feel that they are not supposed to write answers for "trivial questions" - but why do they comment then?

I always ask the person to post it as an answer then. It does not always happen, though. Sometimes I then write a CW answer myself, copying the comment into it (even on questions that I asked myself).

Here are some recent examples where this happened, showing that it just happens too often.

It also happens on mathoverflow on a regular basis.

Personally, I think that we need to have a better solution here. For the start, it would be good to have a reference where it is explained clearly that and why answers should not be written inside of comments. Maybe accompanied with a teaser text that links to this reference. Then we might be able to copy paste this text.

But in the long run, this will not change much, since there are a lot of poeple who are new to the site and just do not know this recommendation. To new users, there should be a popup before they are submitting a comment. Alternatively, there should be a flag option for comments, saying that it is actually an answer.

Let me start something:

This is an answer to the question, not just a comment. Please post your answer as an answer. This brings extra visibility to the answer und puts the question off the unanswered list (otherwise it will be bumped up periodically). Also notice that comments are not indexed by the full text search and don't offer all the features that answers enjoy. Comments should only be used to clarify the problem.

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    $\begingroup$ Making a CW answer certainly is a step up from a comment, and a gesture of personal humility maybe, but honestly it doesn't seem like an intended use for CW. Really in that case what is called for is just a toggle for an answerer to hit when they write a solution saying "I don't want rep for this." It would get the effect one wants without the attachments of making the solution easier to edit by newcomers. Anyhow I have no objection to this use of CW, and I think there is an argument it is not necessary. $\endgroup$
    – rschwieb
    Dec 1 at 15:06
  • $\begingroup$ I agree, but it's maybe the best we can do for now, right? Qiaochu also proposed this (long time ago) here. $\endgroup$ 2 days ago

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