SO has the following two questions:

ERROR: ISO C++ forbids initialization in array new


As far as I can see, the only difference is the case of "ERROR". Does that defeat the duplicate title detection algorithm?

UPDATE: The second question title was edited after I posted this question. The part beginning with note :: wasn't originally there.


How did this duplication happen?

  • 1
    Hmm. Isn't note :: no array is declared with new function aslo a difference between the two titles? ;) – DavidPostill Sep 4 '15 at 7:31
  • @DavidPostill That was added in an edit after I posted the question. – Barmar Sep 4 '15 at 7:32
  • 1
    Perhaps you should edit this question to include this information ;) – DavidPostill Sep 4 '15 at 7:33

The duplicate title filter is case sensitive. It is, I assume, a unique index on the title in the Posts table.

I demonstrated this 3 years ago; the following query produces the most egregious examples:

select top 15 lower(title), count(*)
  from posts
 where posttypeid = 1
 group by lower(title)
 order by count(*) desc

which are:

------------------------------------------------------------------------ -- 
object reference not set to an instance of an object                     59 
regular expression                                                       41 
help with sql query                                                      34 
mysql query help                                                         30 
mysql syntax error                                                       30 
input string was not in a correct format                                 27 
mysql query optimization                                                 27 
jquery selector                                                          26 
uncaught typeerror: undefined is not a function                          25 
mysql query problem                                                      25 
conversion failed when converting date and/or time from character string 24 
regular expression help                                                  21 
null pointer exception                                                   21 
sql query problem                                                        21 
unrecognized selector sent to instance                                   21 

This is what the same query returned in 2012:

---------------------------------------------------- -- 
object reference not set to an instance of an object 44 
help with sql query                                  35 
regular expression                                   33 
mysql query help                                     31 
mysql syntax error                                   28 
mysql query problem                                  27 
mysql query optimization                             24 
jquery selector                                      24 
regular expression help                              23 
sql query problem                                    23 
database design question                             20 
jquery selector question                             19 
jquery autocomplete                                  17 
what does this code do?                              17 
jquery validation                                    17 

Note how the numbers have increased, demonstrating that the title filter definitely is case-sensitive.

As before, if this is important, the simple answer is the create a unique index on lower(title) in the Posts table - possibly after replacing all punctuation.

  • 1
    If it's case-insensitive, how did he manage to create the duplicate title? – Barmar Sep 4 '15 at 12:15
  • 1
    Just double negativing myself to confusion @Barmar. I've edited. – ben is uǝq backwards Sep 4 '15 at 12:16

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