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From: foessmei@lan.informatik.tu-muenchen.dbp.de (Reinhard Foessmeier)
Newsgroups: comp.lang.c
Subject: Re: struct accessing
Summary: structures vs. arrays
Keywords: structures arrays
Message-ID: <640@tuminfo1.lan.informatik.tu-muenchen.dbp.de>
Date: 26 Jun 89 11:23:43 GMT
References: <1545@stl.stc.co.uk>
Sender: news@lan.informatik.tu-muenchen.dbp.de
Reply-To: foessmei@lan.informatik.tu-muenchen.dbp.de (Reinhard Foessmeier)
Organization: Inst. fuer Informatik, TU Muenchen, FR Germanujo
Lines: 46

In article <1545@stl.stc.co.uk> dsr@stl.stc.co.uk (David Riches) writes:
 .....
>Say I have a structure like :-
>
>struct fred
>  {
>   int tom;
>   int dick;
>   int harry;
>  }
>
>Now, I have a variable which tells me the name of the field in fred
>which I would like to look at, e.g. field_name.  So if field_name
>holds the name dick I want to look at fred.dick and so on.
>
 .....
>
>Does anyone have an elegant solution to this?

Since you want to process the		^Car vi volas procezi la erojn
component names of your structure,	de via strukturo, la sola racia
the only reasonable way seems to	vojo ^sajnas la uzo de vektoro
be to use an array instead of a		anstataw strukturo.  Vi povas
struct.  You may #define symbolic	#difini simbolajn nomojn por
names for the indices, e.g.		la indicoj, ekz-e

#define TOM	0
#define DICK	1
#define HARRY	2
 int fred[3];

Now you can access the components	Nun vi povas aliri la erojn kiel
as "fred[TOM]" &ct.  Fiddling with	fred[TOM] ktp.  Procezumi la plenajn
the full strings is probably a		nomojn probable estas mal^sparo de
waste of resources anyway.  Only	tempo kaj spaco.  Nur kiam vi volas 
if you want to read a name from		legi nomon de ekstera dosiero, vi
an external file you have to convert	devas konverti ^gin (ekz-e en
it (in a switch statement, for instance),	switch-instrukcio), sed
but that is the place where conversion	tio estas la ^gusta loko por kon-
belongs.				vertado.

Sorry for my crude English; Those who know ILo may benefit from the right
column.
Reinhard F\"ossmeier, Technische Univ. M\"unchen |  "Lasciate ogni speranza,
foessmeier@infovax.informatik.tu-muenchen.dbp.de |      voi che entrate!"
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