I just came across this question.

As many other questions, the (probably) correct answer is in the comments. Sometimes I also post short, quick, and obvious answers in comments, and provide a detailed answer as soon as I have a little spare time (e.g. here).

I think also that it's common courtesy that in the meantime nobody clone my comment and post it as an answer. Obviously, other answers with original contributions, or that extend and improve my comment, are welcome.

I've seen on meta some discussion related to this, e.g.:

but I didn't find a conclusive answer. So, with regard to this answer, since:

  • No original contribution WRT the comment (or at least let's assume this for the sake of this question),
  • No credits to commentator,
  • Answered just (few) minutes after the comment instead of giving the commentator the chance to write his own complete answer,
  • Answer not as Community Wiki,

my questions for MSO are:

  1. Is it correct / fair behavior to provide answer copied from other's comments?
  2. Should I flag the question? If so, which flag will be appropriate?
  3. Should I just live with that and next time post from the beginning a full-featured answer?


The intent of this question is not to take action against the user who posted that answer. This is just an example used to explain my doubts on how to handle such situation.

  • 10
    How do you know he read the comment? He only answered 11 minutes after you commented and some of that time must have been spent writing the answer. Sep 2 '15 at 18:42
  • @RobertLongson I don't know that. But assuming he did read the comment, what do you think?
    – Miki
    Sep 2 '15 at 18:45
  • 21
    That's the problem. Assuming. Gets you in to trouble mostly. Sep 2 '15 at 18:48
  • Trivial answer for a common problem. Your example isn't that exemplary.
    – user1228
    Sep 2 '15 at 18:53
  • I probably used a poor example for my question, but I appreciate your insights. Thank you very much.
    – Miki
    Sep 2 '15 at 19:00
  • In your first example, the correct answer (to the full question, if not the one in the title) appears to be in the last comment (by user3386109). In general, a comment should be cited if it was used, but in many cases the answer and the comment could be being created without knowledge of each other.
    – TripeHound
    Sep 4 '15 at 14:51
  • @TripeHound agreed. But that's posterior to this post. And should probably be posted as an answer and not as a comment :D
    – Miki
    Sep 4 '15 at 14:55
  • Doubts? In the Indian sense or the regular sense? Sep 4 '15 at 15:02
  • @PeterMortensen I'm not native english, nor indian, so I can't tell :D. doubt: "a feeling of being uncertain or unsure about something"
    – Miki
    Sep 4 '15 at 15:10
  • Taking a comment and making it into a good answer benefits the users of this site and should be encouraged. While I would not go so far as to penalize the user that incorrectly posted an answer as a comment, I would not go out of my way to reward them either. (Notice the irony of this being posted as a comment?)
    – picciano
    Sep 4 '15 at 15:17
  • 1
    The goal of SO is not to get you "credit". The goal is to give the OP the answer they need (assuming their question is valid and well-asked) and preserve the knowledge of that question and answer for anyone who has the same issue in the future. If you want rep, answer questions. If you want to quickly help the OP, go ahead and answer it in the comments, but don't get upset when someone drops by and fixes it by making the information in your comment useful to and searchable by others by posting it as an answer.
    – Blackhawk
    Sep 4 '15 at 17:02
  • @Blackhawk I partially agree with you. I don't care that much about rep, I just wanted to know the "etiquette". As soon as the OP problem is solved, great! But a user can easily go through all the questions with answer in comments, post them as answers and gain A LOT of rep. I think this is somehow against the rules of SO. The problem would be solved if this user, since the goal isn't to get "credit", posted those comments as Community Wiki answers.
    – Miki
    Sep 4 '15 at 17:08







  • 1
    A flag would be definitely inappropriate. In this case the answer also has an explanation how it works, the comment doesn't.
    – user000001
    Sep 2 '15 at 18:53
  • 2
    @user000001 Well if the use really did copy content from a comment they need to cite it, even if they add onto it. The content that is quote does need to be cited, and not citing it is plagiarism.
    – Servy
    Sep 2 '15 at 18:56
  • 20
    One of the main reasons I see comments that can answer a question is mainly due to asking the user to try something simple that might solve their problem (sometimes due to not being able to run the users code). But not being sure if that's going to really solve the problem. Such as "Did you make sure to include xyz library?" or "It looks like you forgot to do xyz first, that could cause an issue". Sep 2 '15 at 19:05
  • This answer gets the main points across very well as to why this should be allowed to happen. I wish to supplement with one additional point. I feel that there is also a useful editorial function for SO of having workable solutions found in comments recast as answers for easier voting and and easier discovery by other SO users (this is in support of @Servy's second and third points). Sep 3 '15 at 20:55
  • 1
    You are getting all up in arms over hypothetical plagiarism (in your comments on others' answers). Can you provide a better example than the OP (a nontrivial question, for starters) where someone promoted another's comment to an answer and would be (in your opinion) guilty of plagiarism if they left out attribution to the comment? I support your position in principle, but it's really hard to make a nontrivial contribution via a comment and I see attribution as a matter of courtesy, not justice, much less law.
    – Frank
    Sep 4 '15 at 15:05
  • 1
    You can also just edit in attribution in the case where it's absolutely clear, no need for flags. Sep 4 '15 at 15:06
  • @MatthewRead You should still be flagging the post in such a case, so that if there is a history of plagiarism it will become apparent to the mods.
    – Servy
    Sep 4 '15 at 15:48
  • 1
    A flag would be inappropriate before you had asked for the citation in a comment. (This does not mean it is appropriate after, it just means it is definitely not appropriate before). Do not bother mods with something you can at least attempt to handle yourself. Sep 4 '15 at 18:47
  • @Yakk No, that's just not the case. If you notice a case of plagiarism it's entirely fine to just flag the post and let a mod resolve the issue. You are in no way obligated to try to fix the problem on your own.
    – Servy
    Sep 4 '15 at 19:19
  1. is it correct / fair behavior to provide answer copied from other's comments?

In general it is OK to "steal" answers from other user's comments IMHO. If so it's fair to mention that comment explicitly, if it inspired the answer.

But be aware there may be good reasons, why other users have chosen to post this as a comment, and not as an answer.
Such include, the question shouldn't be answered because of uncleanness, being too broad, or otherwise not fitting well for the desired Q&A format of StackOverflow and future research.

  1. should I flag the question? If so, which flag will be appropriate?

Well, if you're absolutely sure that answer should be a comment, flag it as Not an answer

  1. should I just live with that and next time post from the beginning a full-featured answer?

Best this might be padawan.

  • 2
    +1 for "be aware" section, too often I see my comments being transformed as answers on questions I VTC...
    – Kaiido
    Sep 3 '15 at 5:25
  • 16
    I frequently post comments which contain the "seed" of a good answer, basically because I don't have the time to flesh it out yet; In those cases, I'm usually hoping someone will "steal" my comment and turn it into a proper answer.
    – Gus
    Sep 3 '15 at 19:22
  • 3
    So much this Gus. I usually comment at work with hypotheses and answers at home if nobody has used the hypotheses as a seed. I don't have the time and the tools to check my hypotheses at work - but someone else might agree they are very likely and actually check to form a complete answer.
    – Mystra007
    Sep 3 '15 at 21:34
  • 1
    @Mystra007 I'm doing in a similar manner. Unfortunately at home I'm limited to my tablet ATM. Sep 3 '15 at 21:37
  • 1
    +1 @Gus. I often do something similar. It might "be" the answer, but I'm not in a position to test/verify it, or I'm in "debug" mode: "try ...." and see if it either fixes the problem or narrows-down what's going wrong. Until the OP has tried, I won't know if it's an answer or not (and in one recent case, I declined the OP's offer to create an answer because my comments only led the OP to solve the problem themselves, but I didn't provide the answer).
    – TripeHound
    Sep 4 '15 at 14:49

My opinion is different from the accepted answer.

I think it would be fine to just post an answer without any attribution to the commenter and then flag the comment as obsolete.

Giving attribution to a comment that has since been deleted is just noise.

If the commenter cared about getting credited for the idea they should have posted it in answer format in the first place.

In the case that a comment was somewhat speculative and turned out to be correct my personal etiquette (which seems quite commonly held) is to ping the commenter indicating that they should post it as an answer rather than just leaping in there with an answer stating the same thing though.

  • 1
    You can still link to the user, which presumably won't be as short-lived. Though that depends on how much is your own, and how much the comment contributed. Sep 2 '15 at 20:41
  • 6
    @Deduplicator Unless the comment is copied more or less verbatim I don't see the need. (And answers should be more substantial than comments anyway so the exact copying issue shouldn't arise.) Giving generic thanks to other users lowers the signal to noise ratio too. If a correct answer is posted in the comments I don't think the commenter should have any expectation that a correct answer in the answer section (which will necessarily have similarities) will acknowledge the comment at all. Sep 2 '15 at 20:55
  • 3
    What you're describing is called plagiarism, and while you personally may not have a problem with plagiarism, SE policy, and the laws of most countries, make it very clear that plagiarism isn't acceptable behavior.
    – Servy
    Sep 3 '15 at 20:59
  • 4
    @Servy as long as the comment isn't repeated word for word how can you possibly tell it is plagiarism (hint you can't). So how can that be enforced by "laws of most countries"? The idea that attribution should be required if and only if you didn't already know the answer on an honour system seems simply unworkable and unnecessary. Sep 3 '15 at 21:03
  • 2
    @MartinSmith Content doesn't need to be repeated word for word to be plagiarized. If you think that laws, and enforcement agencies, are really that dumb, and that any content not repeated word for word is never vulnerable to an IP claim, then you're likely to find yourself in serious trouble at some point in your life. And even if your assumption that it's unenforceable is true, you're basically trying to say, "I know what I'm doing is wrong, but I'm probably not going to get caught, so it's okay." Which, even if you don't get caught, doesn't make it right.
    – Servy
    Sep 3 '15 at 21:08
  • 1
    @Servy "I" don't do that at all. I'm much more likely to be the commenter in this scenario. And I wouldn't expect any attribution at all from anyone posting an answer along the same lines irrespective of whether they learned it from my comment or a book or somewhere else, and I would have no way of telling anyway. Sep 3 '15 at 21:12
  • 3
    @MartinSmith The fact that you don't care if your content is plagiarized doesn't mean nobody else cares, doesn't mean that it's appropriate, and doesn't make it okay for you to advocate that others freely plagiarize people's content. If you want to make the content that you provide a part of the public domain, so that it doesn't require attribution to re-use, you can do that, but as it is, all contributions provided by every user on SE maintain that user's copyright of their content, and you're advocating that people violate that right.
    – Servy
    Sep 3 '15 at 21:15
  • 3
    Comments are ephemeral. Preserving them in an answer - assuming that it stands in it's own right - is fine. There's no problem with that. Summarising in your own words I wouldn't even call plagiarism, any more than I would copying out the graffiti in a toilet cubicle.
    – Sobrique
    Sep 4 '15 at 14:57
  • 1
    @Servy SE uses CC-BY-SA, the user does not maintain copyright. Personally I would also doubt that a short factual comment intended to share the information it presents constitutes a work protected by copyright. Sep 4 '15 at 15:10
  • 4
    @MatthewRead That's a strictly false statement. SE's licence in no way removes the owner's copyright. All it does is state that the user is allowing anyone to publicly use or build on the provided content as long as it is attributed appropriately. That doesn't remove copyright. The author still has all of the other associated rights, except for the right that the licence states they're giving up. Your statement that the work isn't intended to maintain copyright is just strictly false. It absolutely is, and it would need to explicitly give up that right for it to not be there.
    – Servy
    Sep 4 '15 at 15:45
  • @Sobrique You may not call it plagiarism, but the law, SE policy, and just about an official source I've ever seen attempting to define the term does. Summarizing someone else's content doesn't mean that you can suddenly claim that content as your own original work. You still need to cite it.
    – Servy
    Sep 4 '15 at 15:46
  • 1
    @MatthewRead: You have that backward. SE uses CC-BY-SA, which absolutely depends on copyright; without it, the "BY" (attribution required) and "SA" (users must re-share under similar terms) parts would not be enforceable.
    – ruakh
    Sep 4 '15 at 16:34

It's fine. Comments are second-class citizens and subject to removal at any time. In this case, because of the simplicity of the answer and comment, you could argue that the answer makes that comment obsolete. If the other user didn't bother posting an answer (for whatever reason), that's too bad.

By answering, the user takes ownership of a post and prepares to accept responsibility for it. This includes maintenance, explanation, and all votes (up or down) for the post. The commenter probably should have answered the question directly, but the existing answer is fine.

That being said, there are some courtesies you can employ. Attribution is only necessary for cases where the answer incorporates the comment. Since in this case the answer was pretty simple and could likely be found independently, "attribution" would really just wind up being a reference to a FGITW comment. Community wiki is an extension of this idea to give credit to the comment, but it's a courtesy and not required. The existing answer provides more explanation than the comment anyway, so the addition of original content really makes the community wiki a poor choice in this case.

  • 6
    It is not universally acceptable to plagiarize content in comments. If you're going to use someone else's content, even if it's from a comment, you need to cite the source. Of course, in this particular case, it seems pretty likely that the author simply came to the same conclusion independently.
    – Servy
    Sep 2 '15 at 18:58
  • 2
    @Servy updated to clarify what I actually meant. If you still disagree, I'd appreciate a comment on the specific point of contention.
    – ryanyuyu
    Sep 2 '15 at 19:12

Disclaimer: extremely subjective

I would say that people who take the answer out of a comment and submit it AS AN ANSWER are doing the community a great service, whether they credit the commenter or not.

I'm rather biased, but I'm often frustrated by questions which are answered in the comments. If I'm looking for a solution to the same problem as the OP, I either skip over those questions since there are no posted answers (or at least no accepted answers) or I spend 20 minutes reading through the often extraneous narrative of the comments to find that one useful tidbit of information that tells me what I actually need to know. If I'm trying to answer a question, I will start typing up an answer until I notice the "Thanks! That solves my issue." in the comments - great, I just wasted time I could have spent helping someone who needed it.

If the original comment-answerer wanted the rep, they could have posted as an answer in the first place. If a back and forth conversation in the comments was necessary to find the answer, they still the opportunity to post it as an answer afterwards. If they choose not to for whatever reason, it should be encouraged for those who want the rep to come and clean it up after them by posting the answer. Rep is the oil that greases the SO machine and incentivizes the less glamorous parts of site upkeep.

In conclusion - while answering in the comments may help quickly solve the OP's issue, it does nothing for future Askers or Answerers - let's encourage people clean it up for posterity.

  • 2
    Just note that, while taking a comment and writing it up as an answer can be very helpful, you still need to cite the source. There's nothing wrong with using that person's content; by posting it on SE they've implicitly given you the write to reproduce and reuse that content as long as you're citing it appropriately.
    – Servy
    Sep 4 '15 at 18:03

Someone attempting to claim plagiarism without attribution when the original content is on the same webpage would be an interesting court case. The attribution of the content is on the same webpage with an earlier time stamp: How close does the attribution have to be to the plagiarism?

Now, when/if the comment is deleted, things get a bit worse. But who violated the license, the person who deleted the attribution, or the person who posted the plagiarism?

If you notice it, post a comment asking for attribution. If that is rejected, and you still think the plagiarism is likely, flag the post.

Flagging first when you can attempt to handle it yourself is not very polite to the mods.


Copying whole comment and posting it as an answer without any change is totally wrong. If answer uses the comment as a base and improvise it in a better way than it's completely fine.

But apart from that I want to bring the attention to the comment section, it is clearly stated that we should avoid answering in comments and use comment section exactly for which purpose it is made. To critique or clarify. So, at the same time users who attempt to provide answer in comment are also breaking the rule.

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  • "users who attempt to provide answer in comment are also breaking the rule" - well, depends. Providing an answer can be a way to ask for clarification. When OP confirms that it works, it is a sign that the question is clear enough to answer. Also, comments are good for answering questions that should be closed for typographical errors.
    – klutt
    Jun 24 '18 at 3:40

(Disclaimer: I believe very strongly that the current SE-wide treatment of comments as second-class and ephemeral is wrong and should cease immediately if not sooner.)

If someone posted a comment that appears to answer the question, rather than writing a full answer, they probably had a good reason for it. For instance:

  • The comment only looks like an answer. It points out the most obvious bug in the questioner's code, which may or may not be the cause of the problem they are asking about.

  • The comment is only a partial answer, because the commenter does not know everything required to provide a complete answer, but recognizes part of what is going on.

  • The question is about to be closed as a duplicate. The commenter wants to give the questioner a more positive first encounter with SO by answering them directly.

Regardless of the reason, you should respect the commenter's intention, by not converting such comments directly into answers.

If you recognize a partial answer as such, and know how to give a complete answer, the appropriate thing to write is "As pointed out by [soandso] in the comments, [partial answer in your own words], but that's only part of the problem; [further explanation]." Similarly, if you independently come to the conclusion that somebody's comment is a complete answer to the problem, "As pointed out by [soandso] in the comments, [answer in your own words]" is appropriate.

  • 2
    So I can write a FGITW comment on an obvious question and either it should block other answers or anyone that provides a proper answer afterwards is obliged to acknowledge me? Sep 3 '15 at 21:21
  • I don't know what you mean by FGITW.
    – zwol
    Sep 4 '15 at 3:09
  • 1
  • You should absolutely disregard the commenter's intention as to whether a suggestion is an answer. No one user gets to dictate universal truth over any problem. Sep 4 '15 at 15:13
  • Your reasons why someone might post a comment are good -- I've posted comments for essentially all of them -- but have never done so with the intention that by doing so, there shouldn't be answer. If someone did comment with that intention, I think the problem lies with the commenter not the answerer.
    – TripeHound
    Sep 4 '15 at 15:16
  • @TripeHound I think you misunderstand. I am not saying there should not be an answer, I am saying you should not copy-and-paste a comment into an answer, for the reasons above.
    – zwol
    Sep 4 '15 at 17:11
  • @MatthewRead See response to TripeHound and imagine that I added something snide at the end of it.
    – zwol
    Sep 4 '15 at 17:12
  • I wouldn't do so, if the question is live/active: I'd give the original commenter (OC?) a chance to follow up, so in that sense I agree one shouldn't (but doing so probably isn't "not allowed"). Once a "suitable" time has passed, and it seems plausible the OC may not be back, then things would be different.
    – TripeHound
    Sep 4 '15 at 17:24

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