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Date: Wed, 28 Jun 2006 18:01:33 +0000 (GMT+00:00)
From: "Martin Sebor (JIRA)" <jira@apache.org>
To: stdcxx-dev@incubator.apache.org
Subject: [jira] Created: (STDCXX-216) std::map::insert (iterator, pair)
 doesn't use hint properly
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std::map::insert (iterator, pair) doesn't use hint properly
-----------------------------------------------------------

         Key: STDCXX-216
         URL: http://issues.apache.org/jira/browse/STDCXX-216
     Project: C++ Standard Library
        Type: Bug

  Components: 23. Containers =20
    Versions: 4.1.2, 4.1.3   =20
 Environment: all
    Reporter: Martin Sebor


Moved from the Rogue Wave bug tracking database:

****Created By: sebor @ Mar 23, 2004 04:17:39 PM****
http://www.roguewave.com/developer/forum/OpenForumThread.cfm?forum=3D100&th=
read=3D542
----------------------------------------------------------------------
Topic:Error in map::insert
----------------------------------------------------------------------
map::insert( iterator, pair) does not work    (11/06/2003 02:13 AM)
----------------------------------------------------------------------
I wanted to use the map::insert( iterator, pair) method to speed up things,=
 but
my tests
showed that it was slower than the simple insert.
Debugging showed that the test for usability of the position iterator alway=
s fails:
iterator before =3D --position;
if (_key_compare( before.first, (key) v) && _key_compare( (key) v,
position.first)) ..

Reason: 'before' and 'position' are equal, and (more simple term)
a < b && b < a
is always false.

I guess it should read
iterator before =3D position;
--before;

I found the same problem in STL library with CPP Builder 5 as well as on Su=
n
Solaris 8,
Sun Workshop 6 update 1 C++ 5.2 Patch 109508-09.

Has anybody found this error too? Or, can anyone tell me in which version i=
s it
fixed?


Another point is: Accoring to the manual the iterator should point to the l=
ast
element smaller than the element to insert. If the code would be changed as
suggested above, it would work if the iterator pointed to the next-greater
element in the map ...
To make it work as described, the code would have to be
iterator after =3D position;
++after;
if (_key_compare( position.first, (key) v) && _key_compare( (key) v,
after.first)) ..

But I did not check the following insert methode if a pointer to the elemen=
t
before or after the new one is required, so it may need even more code chan=
ges
or a change of the description...

Hth anybody else too, and maybe sbd can tell me in versions this problem is=
 fixed?
Thx in advance!
Ren=C3=A9
=09=09=09=09=09=09=09=09=09=09
----------------------------------------------------------------------
Re: map::insert( iterator, pair) does not work    (11/17/2003 04:49 PM)
----------------------------------------------------------------------
We are not aware of this problem. The use of the hint argument by insert() =
isn't clearly specified in the C++ standard (in fact, there is an open issu=
e on it -- see
http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/lwg-active.html#233). We'll look=
 into it.

Thanks
Martin

--=20
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