A few times someone has commented on my question with the solution to my question. I'm not sure why they didn't post it as an answer. There's a flag for "not an answer" but no flag for "this is an answer".
Can it be converted to an answer with a flag? Or should I just comment back saying they should post it as an answer and I will mark it as the answer.
I don't really want to post it as an answer myself and then mark it as an answer as I feel I'm stealing their rep
There is no functionality like that unfortunately, and it'd be a nice feature as well as being able to directly convert a not an answer flag into a question.
I know this is something I am guilty of from time to time. Sometimes it is to provide a quick thing to check an not a full fledged detailed answer.
If the commentor is responsive, they will generally convert that comment to an answer so it can be accepted. If they don't, then it is acceptable to use their comment to supply your own answer. If in the future they do come back and supply an answer, you are free to unmark your answer as the accepted answer and award it to them.
This happened to me recently, and another user copied my comment and got credit for the answer. Oh well.
The reason I added it as a comment was that I didn't think or wasn't sure it was really the answer. If I'm just taking a wild guess, I'm not going to submit an answer. I care more about the quality of my contribution to this site than I care about maximizing my point total.
I can speak for myself only, but I think actually many other may share this view.
I have done this multiple times both in the past and recently. Not considering times I had a comment posted because I didn't had the time to post a full answer but still wanted to leave a possible hint to the user, most of the other comment-answers fall under a simple reason.
When I post an answer, I like to be sure that it actually qualifies as an answer - not just a GUESS.
Very often I see answers that are just guessing what the problem may be. Any time an answer starts with "Maybe", Have you tried looking at the logs", "Try to do this and see what happens" etc, this is a clear indication that what we post isn't yet an answer but just a still-ongoing "debugging" process that probably would have been better handled as a comment.
Bear me, I am not saying that this is completely to blame on the user answering. After all, many questions are very poorly written in the first place and lack the environment information that are required to craft that one "sure-to-work" answer in the first place. I also can understand how this "guess answer" may be view from many users as a "I came first" answer preorder - every time you post what may become an answer as a comment because you are not sure you are actually risking some evil one coming steal your idea and the unicorn points prize.
More seriously: I think it is only a matter of preferences. Some users prefer to only use an answer if they are sure that they know the problem and using "Try this" comments otherwise, other prefer acting boldly and posting the guess directly as an answer (knowing it may be downvoted) and then edit or delete it as required. I personally prefer the first approach, but this is only my own viewpoint. You should chose what seems to fit better for you.
As for the related problem, what to do when this happen... I think that common etiquette should suggest that the question asker tries to ask the comment-poster to convert his post to an answer and if that fails. If that fails after a reasonable time, post a community answer with the original comment content so that you won't gain an "unfair" benefice from it.
