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List:       kde-devel
Subject:    Re: QString or QCString for file names?
From:       Waldo Bastian <bastian () ens ! ascom ! ch>
Date:       1999-06-24 10:32:23
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Pietro Iglio wrote:
> There is at least a filename stored for each menu entry, both in 
> the application menu and in the kdisknav menu, plus two pixmaps 
> names (large/small) and a comment for each entry.

Are just the filenames stored or the full path? Are they stored
as URLs?

> If you use intensively kdisknav you can easily allocate, eg., 
> 150 menu entries. Considering  an average length of 10 chars for 
> each filename, you can save something if you don't use QString.

Let's see 4 filenames * 150 entries = 600 entries.

With QString:
Assuming an average length of 10 chars: 
Approx. 40 bytes per string.
Approx. 24000 bytes.

Assuming an average length of 30 chars (including path):
Approx. 100 bytes per string.
Approx. 60000 bytes.

Possible memory use when using simple char *:

Assuming an average length of 10 chars: 
Approx. 10 bytes per string.
Approx. 6000 bytes. (Saves 18K)

Assuming an average length of 30 chars (including path):
Approx. 30 bytes per string.
Approx. 18000 bytes. (Saves 42K)

I don't think 42K is worth to bother. It would be if it could
be saved in every application, but your normally run only 1 instance
of kpanel anyway. If you have 1500 menu entries instead
of 150 it could be worth it.

Does that happen?

> > With respect to CPU:
> > Profile your code to see where the problems are. Guessing about
> > performance problems is plain stupid. (Though very populair)
> 
> You are right, this is the general rule. However, it is not really
> easy to profile the time spent for all qstring operations, unless 
> you have a block profiler.

I tried gprof some time ago but it doesn't really seem to understand
the code very well.

Cheers,
Waldo
-- 
KDE, A New Millennium, A New Desktop                      http://www.kde.org

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