Concatenating tokens that aren't parameters, in ANSI C

[~XT4103000~Marc Mengel~C25~G25~6184~]

In article <4963 at hoptoad.uucp> gnu at hoptoad.uucp (John Gilmore) writes:
[old code breaks under ANSI cpp follows]
>#define LFD 6
>#define LHIGH 1.0e+LFD
>which expanded to
>1.0e+6
 [tried]
>#define LHIGH 1.0e+ ## LFD
 [and also]
>#define cat_a(a,b) a ## b
>#define cat_b(a,b) a ## b
>#define LHIGH cat_a(1.0e+,cat_b(LFD,))
>
>should work, but it produces:
>
>1.0e+cat_b(6 ,)  

Hmmm. seeems like maybe
#define LFD	6
#define BASE	1.0e
#define LHIGH	LFD+BASE

might just work, I don't have a gcc cpp handy to test it though. (It
works under SysV cc.

>John Gilmore    {sun,pacbell,uunet,pyramid,amdahl}!hoptoad!gnu    gnu at toad.com


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