Yesterday someone edited my question and converted all of my un-encrypted http:// links to protocol relative //.

At first I was like "Sweet catch!" because I'm always getting on to our webmaster for a nasty habit they have of hard-coding insecure sources to images, js, and iframes with src="http://... which flat out won't work over a secure https:// connection. (At least not without a bunch of permissive "I understand the consequences" clicks on behalf of the client.) So I try to use protocol relative links across the board for a lot of reasons.

But then I noticed all of those linked questions I made to other SE posts disappeared from the "Linked Questions" sidebar. So to test, I rolled back those changes, and the sidebar returned.

This question is very closely related to Relative links are ignored by “Linked Questions”, but I expect some more trickery is involved with host (or folder) relative links rather than protocol relative links.

It's also interesting to note that both http:// and https:// links are recognized as a "linked question." So my specific question is: Why aren't protocol relative links recognized as linked questions? But this question can be deleted if we can get an authoritative answer to How does Stack Overflow find 'Linked' questions?


1 Answer 1


Because this:

public static Regex GetQuestionUrlRegex()
    return new Regex(@"https?://" + Regex.Escape(Current.Site.BaseHostAddress) + @"(?:/q(uestions)?/(?<qid>\d+)|/a/(?<aid>\d+))", RegexOptions.IgnoreCase);
  • 1
    Are you allowed to expose source code out in the open? ;-) Jun 16, 2016 at 21:28
  • 6
    @ShadowWizard We would never...
    – Adam Lear StaffMod
    Jun 16, 2016 at 21:34
  • @Adam touché... Jun 16, 2016 at 21:44
  • Since neither my c# nor regex skills are worth a dime, can you tell me how difficult this would be to modify it to allow a blank http(s)? Jun 17, 2016 at 2:39
  • Could be as simple as deleting 7 characters, but might get complicated if this is used elsewhere. Regardless, one more thing that'll have to be fixed eventually.
    – Shog9
    Jun 17, 2016 at 4:06
  • 1
    This regex has since changed to cover relative links. Can you please edit this with the latest regex? Sep 27, 2019 at 17:26

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