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solution for macro
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dhun  
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 More options 8 Nov, 00:23
Newsgroups: comp.lang.c++.moderated
From: dhun <mdhua...@gmail.com>
Date: Sat, 7 Nov 2009 18:23:50 CST
Local: Sun 8 Nov 2009 00:23
Subject: solution for macro
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Hi All,
I have a following kind of situation.

#define i(p) p
#define r(x) i(in)##_##x

int main(){
#define in a
int a,a_b;
a = r(b);
#undef in

}

where I need to construct a symbol ab, at the place where code is
executed.

A g++ -E test.c, however insert a space between a and b.

What could be possible solution for this?

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Bart van Ingen Schenau  
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 More options 8 Nov, 15:52
Newsgroups: comp.lang.c++.moderated
Follow-up To: comp.lang.c++.moderated
From: Bart van Ingen Schenau <b...@ingen.ddns.info>
Date: Sun, 8 Nov 2009 09:52:30 CST
Local: Sun 8 Nov 2009 15:52
Subject: Re: solution for macro
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To get the correct substitution for all macro parameters, you need
another two levels of macros.
This example give the required result:

#define i(p) p
#define r(x) r2(i(in),x)
#define r2(p,q) r3(p,q)
#define r3(x,y) x##_##y

int main(){
#define in a
int a,a_b;
a = r(b);
#undef in

}

Bart v Ingen Schenau
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a.c.l.l.c-c++ FAQ: http://www.comeaucomputing.com/learn/faq
c.l.c FAQ: http://c-faq.com/
c.l.c++ FAQ: http://www.parashift.com/c++-faq-lite/

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      [ comp.lang.c++.moderated.    First time posters: Do this! ]


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