Comments on: C conundrum (below)

By: me

me — Thu, 27 Dec 2007 14:14:03 +0000

If you want to do people a favor, update your blog post with the solution you chose (or post another one)

By: Joseph

Joseph — Thu, 27 Dec 2007 00:27:50 +0000

http://gcc.gnu.org/onlinedocs/gcc-4.2.2/cpp/Concatenation.html#Concatenation

By: Zack

Zack — Wed, 26 Dec 2007 22:19:29 +0000

I am not sure I understand your example but I believe this is the construct you want:

#define S(x) S_(x) #define S_(x) #x ... some_function_which_takes_a_string ("String literal with FOOBAR concatenated: " S(FOOBAR));

By: Philip

Philip — Wed, 26 Dec 2007 22:08:53 +0000

Thanks everyone. Benjamin's suggestion is the most useful, since what I'm working on uses Glib, but I'm grateful for others' suggestions too. I feel a bit of an idiot now, as the solution's so simple. Live and learn.

By: ion

ion — Wed, 26 Dec 2007 20:54:53 +0000

Sorry, please ignore my previous comment. I misparsed the question due to my browser not rendering the code with any line feeds.

By: ion

ion — Wed, 26 Dec 2007 20:50:21 +0000

#define FOOBAR(n) do { foo (n); bar ("baz: " #n); } while (0) FOOBAR (1+2) will call foo (3) and bar ("baz: 1+2").

By: tuXXX

tuXXX — Wed, 26 Dec 2007 16:52:41 +0000

This is described in the gcc C preprocessor documentation ( http://gcc.gnu.org/onlinedocs/cpp/Stringification.html ) :

#define xstr(s) str(s) #define str(s) #s #define FOOBAR 5 [...] some_function_which_takes_an_integer (FOOBAR); some_function_which_takes_a_string ("String literal with FOOBAR concatenated: " xstr(FOOBAR));

After preprocessing, this will be :
some_function_which_takes_an_integer (5); some_function_which_takes_a_string ("String literal with FOOBAR concatenated: " "5");

And then the compiler will concatenate the two strings as :
some_function_which_takes_a_string ("String literal with FOOBAR concatenated: 5");

Hope it'll help you

By: Christian Vogel

Christian Vogel — Wed, 26 Dec 2007 16:45:43 +0000

have a look at the bottom of http://gcc.gnu.org/onlinedocs/cpp/Stringification.html

By: Benjamin Otte

Benjamin Otte — Wed, 26 Dec 2007 16:36:20 +0000

G_STRINGIFY does exactly that for me

By: Noname

Noname — Wed, 26 Dec 2007 16:36:02 +0000

Try the following:
#define FOOBAR 5 #define STRINGIFY(x) #x #define STRINGIFYVALUE(x) STRINGIFY(x) some_function_which_takes_a_string ("String literal with FOOBAR concatenated: "STRINGIFY(FOOBAR)); some_function_which_takes_a_string ("String literal with FOOBAR concatenated: "STRINGIFYVALUE(FOOBAR));