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List:       kde-devel
Subject:    Re: kdelibs/kfile
From:       Matthias Welk <welk () fokus ! gmd ! de>
Date:       1999-06-24 15:43:20
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On Thu, 24 Jun 1999, Waldo Bastian wrote:
> Sirtaj Singh Kang wrote:
> >
> > On Wed, 23 Jun 1999, Hans Petter Bieker wrote:
> > [snip]
> > > I tried to create my own compare():
> > > bool compare( const QString &as, const QString &bs )
> > > {
> > >     if (as.length() !=3D bs.length()) return false;
> > >     const QChar *a = as.unicode();
> > >     const QChar *b = bs.unicode();
> > >     if (memcmp(a, b, as.length() * sizeof(QChar)) != 0)
> > >         return false;
> > >     return true;
> > > }
> > >
> > > That code seems to work, but uses only:
> > > real    0m0.681s
> > > user    0m1.562s
> > > sys     0m0.062s
> > >
> > > What am I missing?
> >
> > Hi,
> >
> > Well memcmp is not enough for a string comparison function is it?
> > strcmp returns
> >         < 0 if string 1 is greater
> >         > 0 if string 2 is greater
> >         = 0 if strings are equal
> >
> > This means that the QChars will need to be tested if the strings
> > are not found to be equal after the first test.
>
> Perhaps we should have a
> "bool equal(const QString&, const QString &, int len=-1)"
> function which just does the above. Often you are not interested
> if a string comes alphabetically before or after the other.
>

The Trolls changed the == operator in their newest CVS-Snapshot to use
the memcmp approach :-) (according to the cvs log its 200% faster)

Greetings, Matthias.
--
---------------------------------------------------------------
From: Matthias Welk                   voice: +49-30-3463-7272
      GMD Fokus                       fax  : +49-30-3463-8272
      Kaiserin-Augusta-Allee 31       email: welk@fokus.gmd.de
      10589 Berlin
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