Scholarly Resources for CompSci Undergrads

C Programming Language

Annotations on K&R II

Expansion about comment on p. 90

Here is an excerpt from the 1 November 1995 version of the comp.lang.c frequently asked questions list. The list is Copyright 1990-1995 by Steve Summit.

11.17:	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 can use something like the following two-step procedure to
	force a 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 code 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., Sec. example; ISO
	Sec., Sec.

A full citation record for the FAQ (and expanded book version) is in my list of technical books.