Every week or so you get, say, a question about the difference between '==' and '===' in PHP. Of course it inevitably gets closed as a duplicate but some people apparently feel the need to leave comments like 'Already asked! God! (roll eyes)' Well you can't actually search for something like == or === unless you happen to know what it's called.

Can we extend the search to allow for these characters?

  • 4
    Definitely the cause of a lot of duplicate questions on Stack Overflow, and likely other symbol-dependent sites as well (Math Overflow comes to mind). Would upvote if I had 15 rep!
    – user146487
    Jun 23, 2010 at 15:35
  • 1
    Example of myself experiencing this issue today: stackoverflow.com/questions/3408818
    – brainimus
    Aug 5, 2010 at 3:48
  • This post is a very light illustration of the problem: meta.stackexchange.com/questions/9686/… Mar 10, 2011 at 15:28
  • Only in the title? Searching for, for example, == might otherwise show a lot of hits...
    – Arjan
    Aug 15, 2012 at 16:51
  • @JakubHampl, same thing i tried 4 different ways but this post never came up
    – Biswajeet
    Apr 23, 2015 at 5:07

4 Answers 4


Stack Overflow really should extend the search to include symbols. There's a gigantic gap in the market for this. See this frustrated Google user:

Programmer-friendly search engine?

Duplicate questions is a cost that Stack Overflow must accept as a consequence of not having this feature. And it should accept it cheerfully, and not grudgingly, until it gets its act together and adds it.



SymbolHound: Search Stack Overflow for special characters

SymbolHound is a search engine that doesn't ignore special characters. I was always frustrated that I couldn't search for symbols like >> and && using Google or the custom Stack Overflow search, so I made a search engine for programmers. It currently searches mostly Stack Overflow pages, with plans to eventually index a much wider range of programming websites (including symbols, of course).

  • 4
    That's cool for experienced users like Cletus, but how will that help new users find already-asked versions of their questions? Feb 2, 2012 at 17:42
  • It won't. People don't know about it until they ask a duplicate question, get PO'ed at the super-ego-users closing their question and eventually find this still-open question on the topic.
    – o_O
    Aug 15, 2012 at 5:12
  • @RKS - It's possible to vote to close a question without downvoting it into oblivion. In this case, they're understandable duplicates. In fact, duplicates normally increase the number of inbound paths to the canonical post. Now, if that SymbolHound could be integrated into the SO search, that would rock!
    – jmort253
    Aug 16, 2012 at 2:00
  • That could be the case as well, however, that's not the way it works. Look at my answer posted yesterday and you say one thing against the super-ego-users and you get downvoted into oblivion. Mention something has been open for 3 years with not even a "maybe one day" update and people downvote you into oblivion. People have a problem with someone going against the status-quo like they fear the squeaky wheel.
    – o_O
    Aug 16, 2012 at 5:29
  • Jeff, that's a good suggestion, not great. It can't filter on a code type. I was looking for %*c in C code, can't get the to work on SymbolHound
    – Mike
    Nov 2, 2012 at 19:02
  • Basically users search duplicate question while writing the question itself, so if SE guys can some how integrate SymbolHound's result for Stack groups, it would be great
    – Biswajeet
    Apr 23, 2015 at 5:49
  • It appears it was broken in April 2022. Nov 21, 2022 at 16:35

This is now possible with the new search engine, just put your search in quotes, a few examples:

The search is case insensitive but is otherwise an exact match engine.

  • Searching for "!!" fails. I'm trying to do a search with "!!" (search I want to do: "!!" [ruby]). "!!" is an accepted operator in ruby. I couldn't remember what it's called, though. Searching "!!" returns NO RESULTS. Here's the line showing the number of results found: Could not find any results for "!!" [ruby]; showing 114,952 results for ""!!" [ruby]", The 114,952 results seemed to be only for [ruby] and excluded/ignored "!!"
    – aenw
    Jul 4, 2015 at 10:31
  • Did something change? The first link returns no results, and the third one is broken
    – mbomb007
    Mar 12, 2018 at 19:25

Actually, I voted to close one question today (the exact same question, for Javascript instead of PHP) and pointed to three dupes. Two of them did show up right in the "Related" section in sidebar.

Interestingly, I feel the "exact duplicate search" works pretty well in finding the duplicates (better than the SO search box.) Is the algorithm different or it's wrong feeling?

  • 5
    It has frequently been mentioned that the suggested questions you get when you type in a question title are often better than what you get from the search. This predates the latest search changes however.
    – cletus
    Sep 3, 2009 at 8:48

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