The underscore _ is a valid character in user names, but when searching users on stackoverflow.com/users, it is treated as a wildcard(!), not as a character. For example, when I type w_of__ in the search box, then not only the user shadow_of__soul appears in the search results, but also, e.g, BiscutWoofington. The user Wooff is not shown, which makes sense since it's only 5 characters long and thus doesn't match the pattern w?of??.

This leads me to the following questions:

  1. Is the above behaviour a or ?
  2. Shouldn't _ be treated as a normal character, and ? be used as a wildcard instead?
  3. What characters other than letters and digits are allowed in user names? So far I found spaces and . - ' _.

(Some testing indicates that underscores are treated just like letters and digits in comment notifications.)

  • Wow! I didn't know we had wildcards. Could we please keep them?
    – M. Tibbits
    Commented Aug 31, 2011 at 21:58

1 Answer 1


We allow the following regex in search: \w' \.\- there was minor oversight that meant I did not disable the _ wildcard that is passed in to the search LIKE clause.

I fixed that, it is way too non-intuitive to find. So now, there are no more wildcards for username search.

I dislike the idea of adding * and ? wildcards. This feature is a bit dangerous and performance is somewhat random depending on the position of the wildcard.

  • Thanks for the fix! However, it's a pity that there are no wildcards anymore. I don't care for *, but implementing ? would be nice in my opinion. Commented Sep 22, 2011 at 8:41

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