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List:       kde-devel
Subject:    Re: "Fixed" post-increment operators on iterators
From:       "Aaron J. Seigo" <aseigo () kde ! org>
Date:       2004-10-31 18:32:10
Message-ID: 200410311132.10366.aseigo () kde ! org
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On Sunday 31 October 2004 05:27, Esben Mose Hansen wrote:
> On Sunday 31 October, 2004 12:59, Frederik Schmid wrote:
> > > QStringList::ConstIterator itEnd = matches.end();
> > > for(QStringList::ConstIterator it = matches.begin(); it != itEnd; ++it)
> > >      _keyList->insertItem(*it);
>
> [...]
>
> > The compiler will (almost certainly) move loop-conditions out ouf the
> > loop, so no need to add extra lines in this case.
>
> I have always wondered about that. Unless the container is const, how can
> the compiler know that mycontainer->end() always returns the same value?

exactly, and so it won't, and so caching the return value of end() (or 
length(), or...) almost always results in a speedup (of how much and of what 
impact is another matter)

> Also, why is it we don't use STL? The above could be written as (untested)

probably a combination of the fact that STL support on all the platforms 
people use KDE on has traditionally sucked and that many people aren't 
familiar with the STL.

-- 
Aaron J. Seigo
GPG Fingerprint: 8B8B 2209 0C6F 7C47 B1EA  EE75 D6B7 2EB1 A7F1 DB43
 
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