Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!romp!auschs!awdprime!sanders.austin.ibm.com!sanders
From: sanders@peyote.cactus.org (Tony Sanders)
Newsgroups: comp.lang.c
Subject: Re: Token Pasting
Keywords: C, preprocessor, ##, # variable
Message-ID: <5256@awdprime.UUCP>
Date: 12 Feb 91 00:25:58 GMT
References: <2261@enuxha.eas.asu.edu> <1991Feb11.195439.17787@csrd.uiuc.edu>
Sender: news@awdprime.UUCP
Reply-To: sanders@peyote.cactus.org (Tony Sanders)
Organization: IBM AWD, Austin
Lines: 31
Originator: sanders@sanders.austin.ibm.com

In article <1991Feb11.195439.17787@csrd.uiuc.edu> bliss@sp64.csrd.uiuc.edu (Brian Bliss) writes:
> #define init(keyword)	keyword ## _symbol = \
>                           symbol_alloc ("keyword", keyword ## _type) 
should be:

#ifdef __STDC__
#define init(keyword)	keyword ## _symbol = \
                          symbol_alloc (# keyword, keyword ## _type) 
#else
#define init(keyword)	keyword ## _symbol = \
                          symbol_alloc ("keyword", keyword ## _type) 
#endif

Which I use like this:

#ifdef __STDC__
#define DPV(variable,type)   if (debug) fprintf(stderr, \
    "%s:%d, " # variable " = %" # type "\n",__FILE__,__LINE__,variable)
#else
#define DPV(variable,type)   if (debug) fprintf(stderr, \
    "%s:%d, variable = %type\n",__FILE__,__LINE__,variable)
#endif

It's quite ugly but it works great.  Your mileage may vary.
This works because # keyword converts to "expaned_keyword"
and "foo" "bar" "bat" "baz" converts to "foobatbatbaz".

-- sanders@peyote.cactus.org
First rule of software:  Throw the first one away.
and so on...
I am not an IBM representative and I speak only for myself.