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From: rex@aussie.COM (Rex Jaeschke)
Newsgroups: comp.std.c
Subject: Re: Preprocessor question
Message-ID: <55.UUL1.3#5077@aussie.COM>
Date: 17 Feb 91 14:04:27 GMT
References: <AHUTTUNE.91Feb16230548@silver-surfer.hut.fi>
Organization: Journal of C Language Translation
Lines: 39

> From: ahuttune@niksula.hut.fi (Ari Juhani Huttunen)
> 
> I would like to do the following or something similar:
> 
> #define BLOCK_SIZE 1024
> 
> char *message = "The block size is " # BLOCK_SIZE " bytes.";
> 
> I need the result: "The block size is 1024 bytes."

The following works:
---------------------------------

#define BLOCK_SIZE 1024

#define STR1(arg) #arg
#define STR2(arg) STR1(arg)

char *message = "The block size is " STR2(BLOCK_SIZE) " bytes.";

#include <stdio.h>

main()
{
	printf("message = %s\n", message);
}

You must go through 2 levels of expansion. If you simply use STR1(BLOCK_SIZE)
you get `The block size is BLOCK_SIZE bytes.' instead.

Rex

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Rex Jaeschke     |  Journal of C Language Translation  | C Users Journal
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