I used to think I knew how to insert a link in an answer, using <a href ...> style. I've been doing this for years without trouble.

It doesn't seem to work with the embedded link in this answer: https://stackoverflow.com/a/17318132/120163

If I delete various suffixes of the quoted link text, the link appears.

Am I doing something dumb?

EDIT 6/28/2013: after the problem found/fixed, I had it again in more recent answer I posted. Many of my links I get from Googling; I suspect others do to. It appears that copying the link from the Google search page gets links containing these characters. At this point this is a theory based on my few recent cases with out good evidence to back it up.

1 Answer 1


You seem to have the Unicode Left-to-Right marker character before and after 3793a055-abs.html. Here, I've removed them (which makes the links work):

One can get code coverage without executing code, via static analysis, essentially by slicing your code from each unit test. See the technical paper Static Estimation of Test Coverage.

  • Aha! and Thanks. Hmm. I got this link by copying from (guess what) a web page. I can understand how a zero-width (thank you, Unicode) character would be rendered as zero width in the displayed answer, ... but shouldn't such odd characters be visible in the answer editor window? [How did you spot this?]
    – Ira Baxter
    Commented Jun 26, 2013 at 13:30
  • I spotted it by navigating over the text with the cursor keys. One "left" press seemed to have been ignored. I then produced a hexdump of the input and checked the result. Rendering zero-width characters visibly in edit fields/areas is a neat idea. I don't think any browser does that. Commented Jun 26, 2013 at 13:34
  • All sane text editors show you invisible characters. ...hmm again... I use Firefox under windows. Since you didn't fix my actual answer, I went back to do so. I tried your cursor key experiment several times; didn't see the "ignored" left press cursor move anywhere. I retyped the link completely from scratch, though, and the problem vanished. What you see is NOT what you get.
    – Ira Baxter
    Commented Jun 26, 2013 at 13:44
  • I didn't remark on it, but I've had this problem recently in a few other SO answers, which I'll go fix. I've never had it before, and the sudden rash suggests it is here to stay (somebody's behavior on the web has suddenly changed; why would such zero-width characters be useful in a web link?) It'd sure be nice to be able to diagnose this more easily. Does SO used an editor built into the browser? I thought it was just a really fancy piece of JavaScript provided by SO; if so, it can be fixed.
    – Ira Baxter
    Commented Jun 26, 2013 at 13:48

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