Re: Numeric constants as strings

From: Andy Parkins <andyparkins@gmail.com>
Date: Feb 19, 2007, 10:54 UTC
Message-ID: <200702191055.00203.andyparkins@gmail.com>
In-Reply-To: <vpq1wkm31q4.fsf@olympe.imag.fr>

On Monday 2007 February 19 10:01, Matthieu Moy wrote:

Show 7 quoted lines

> "Shawn O. Pearce" <spearce@spearce.org> writes:
> > I did not even realize that was legal C...  Now if the 40 was in
> > quotes (e.g. "40") then the concatenate rule would apply and we
> > would get a nice argument to printf.
>
> I suppose the solution is to use #HASH_WIDTH_ASCII to tell the
> preprocessor to put the quotes around HASH_WIDTH_ASCII.

I'm afraid that only works when you're token pasting parameters in a #define macro.

For example:

 #define macro(x) "foo" #x "baz"

Then, macro(bar) expands to "foo" "bar" "baz". However, the following does not work:

 #define BAR bar
 #define macro "foo" #BAR "baz"
 
This is because BAR is not a macro parameter.  I've also tried it indirectly:

 #define BAR bar
 #define MAKESTRING(x) #x
 #define macro "foo" MAKESTRING(BAR) "baz"

But this expands to "foo" "BAR" "baz". Also wrong. Equally, using # anywhere but during a #define doesn't work, so I can't simply write

 printf( "%-" #HASH_WIDTH_ASCII "s", string );

Woe is me. :-(

Andy

-- 
Dr Andy Parkins, M Eng (hons), MIEE
andyparkins@gmail.com