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From: db2@pbinfo.UUCP (Vorl. Informationssysteme)
Newsgroups: comp.lang.c
Subject: Re: Using data types before they are declared.
Message-ID: <548@corona.pb>
Date: 14 Jun 89 08:55:18 GMT
References: <10268@watcgl.waterloo.edu>
Organization: Uni-GH Paderborn, Germany
Lines: 38

In article <10268@watcgl.waterloo.edu> awehrmann@watcgl.waterloo.edu (August Wehrmann) writes:
>I have a question: 
>
>Is it possible, (and if so, how?), to use a data type in a declaration
>of say, a union, that has not yet been declared?
>
>[Example omitted]
>
>union Fred {              <--------
>	int 	Number;            |
>	element	Node;     <...........
>};                                 | .
>                                   | .
>typedef struct {                   | .
>	int	Info;              | .
>	Fred	Name;     <--------  .
>} *element;               <...........
>
>Thanks in advance.
>

I would use the following:

union Fred {
	int		Number;
	struct _el_str	*Node;
};

struct _el_str {
	int	Info;
	Fred	Name;
};
typedef	struct _el_str	*element;

I am practising this in my own programs very often.

	D. Aedal
	YACSS (Yet Another CS Student)