Preprocessor

[Suki]

Adding the macro here for ready reference.

#define PP_NARG(...) \
PP_NARG_(__VA_ARGS__,PP_RSEQ_N())
#define PP_NARG_(...) \
PP_ARG_N(__VA_ARGS__)
#define PP_ARG_N( \
_1, _2, _3, _4, _5, _6, _7, _8, _9,_10, \
_11,_12,_13,_14,_15,_16,_17,_18,_19,_20, \
_21,_22,_23,_24,_25,_26,_27,_28,_29,_30, \
_31,_32,_33,_34,_35,_36,_37,_38,_39,_40, \
_41,_42,_43,_44,_45,_46,_47,_48,_49,_50, \
_51,_52,_53,_54,_55,_56,_57,_58,_59,_60, \
_61,_62,_63,N,...) N
#define PP_RSEQ_N() \
63,62,61,60, \
59,58,57,56,55,54,53,52,51,50, \
49,48,47,46,45,44,43,42,41,40, \
39,38,37,36,35,34,33,32,31,30, \
29,28,27,26,25,24,23,22,21,20, \
19,18,17,16,15,14,13,12,11,10, \
9,8,7,6,5,4,3,2,1,0

when i give
PP_NARG(10, 20) ;
msvc8, msvc9 fails with warning C4003, not enough actual parameters
for macro 'PP_ARG_N'

Thanks in advance,
Surya

[Igor Tandetnik]

I'm trying to get the number of arguments passed to a given macro
(using Variadic Macros) as outlined here.
http://groups.google.com/group/comp.std.c/browse_thread/thread/77ee8c8f92e4a3fb/346fc464319b1ee5
Although VS2005 supports Variadic Macros, the above mentioned method
is not working, It is giving C4003. The same is working with gcc
compiler.
Any thoughts ?

Looks like a bug to me. My reading of the standard suggests it should work, and Comeau accepts it (when using C99 mode, C99 being the only currently-ratified standard describing variadic macros).

[Suki]

Indeed it is...

Details here.
http://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=380090#details