TITLE: Stringizing a macro

PROBLEM: jamshid, 25 Feb 94

I don't think I can claim credit for the STR_(x) technique -- I
probably learned it the comp.lang.c FAQ (see ~jamshid/faq/c.faq).


RESPONSE: 

-----This article is Copyright 1988, 1990-1993 by Steve Summit.--------

5.4:	I'm trying to use the ANSI "stringizing" preprocessing operator
	# to insert the value of a symbolic constant into a message, but
	it keeps stringizing the macro's name rather than its value.

A:	You must use something like the following two-step procedure to
	force the macro to be expanded as well as stringized:

		#define str(x) #x
		#define xstr(x) str(x)
		#define OP plus
		char *opname = xstr(OP);

	This sets opname to "plus" rather than "OP".

	An equivalent circumlocution is necessary with the token-pasting
	operator ## when the values (rather than the names) of two
	macros are to be concatenated.

	References: ANSI Sec. 3.8.3.2, Sec. 3.8.3.5 example p. 93.