Possible Duplicate:
Fail of markdown parser detected if _ are used in naked url
YouTube URL parser chokes on underscore and dash

URLs containing an underscore which is not prefixed by an alphanumeric character are incorrectly parsed.


1. http://_
2. http://youtu.be/_-validId     http://www.youtube.com/watch?v=_-validId
3. http://fop/#_cantbeinvalid_


  1. http://_ A magical "> at the beginning
  2. http://youtu.be/-aValidId and http://www.youtube.com/watch?v=-validId
  3. http://foo/#cantbeinvalid Notice markdown at the end

marked as duplicate by Tim Stone, Kevin Vermeer, Robert Harvey Jan 3 '12 at 19:07

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  • This question was asked earlier today: meta.stackexchange.com/questions/117689/… – Robert Harvey Jan 3 '12 at 18:51
  • 1
    Hmm, the auto-linker probably shouldn't even attempt to link the first example... – Tim Stone Jan 3 '12 at 19:02
  • @TimStone - It also shouldn't attempt the last either, because it lacks a TLD, correct? – Kevin Vermeer Jan 3 '12 at 19:08
  • @KevinVermeer That'd probably make sense too, yeah. Checking for some sort of TLD would prevent http://localhost/ from being auto-linked, which sounds reasonable. – Tim Stone Jan 3 '12 at 19:22

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