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From: ckp@grebyn.com (Checkpoint Technologies)
Newsgroups: comp.lang.c
Subject: Re: Preprocessor macro to quote its argument
Message-ID: <21594@grebyn.com>
Date: 25 Aug 90 14:55:15 GMT
References: <1112@mti.mti.com> <1114@mti.mti.com> <1990Aug20.012839.3545@zoo.toronto.edu> <11517@ogicse.ogi.edu> <1990Aug21.175138.24633@zoo.toronto.edu>
Reply-To: ckp@grebyn.UUCP (Checkpoint Technologies)
Organization: Grebyn Timesharing, Vienna, VA, USA
Lines: 23

In article <1990Aug21.175138.24633@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes:
>The right way to fix the notorious `CTRL(D)' problem is to quote the D.
>There is no portable way for the macro to supply the (single) quotes.
>This has been true for a long time; tokenizing preprocessors existed
>well before the ANSI C effort started.

(This is just off the top of my head, so please be gentle...)

Why can't this work?

#define CTRL(ch) ((* #ch) - 64)

It's ANSI only. The single # places it's arg in double quotes, making a
string, and the * returns the first byte of the string.

Now, I know this *could* be a constant expression. In ANSI, should
a compiler treat this as a constant expression, which is allowed in
static initializers etc?
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