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
| #include <stdio.h>
/* The PP_NARG macro returns the number of arguments that have been
* passed to it.
*/
#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
int main()
{
#define A 1
#define B 1
#define C 1
#define D 1
#define E 1
/* Some test cases */
printf ("%d\n", PP_NARG(A));
printf ("%d\n", PP_NARG(A,B));
printf ("%d\n", PP_NARG(A,B,C));
printf ("%d\n", PP_NARG(A,B,C,D));
printf ("%d\n", PP_NARG(A,B,C,D,E));
printf ("%d\n", PP_NARG(1,2,3,4,5,6,7,8,9,0,
1,2,3,4,5,6,7,8,9,0,
1,2,3,4,5,6,7,8,9,0,
1,2,3,4,5,6,7,8,9,0,
1,2,3,4,5,6,7,8,9,0,
1,2,3,4,5,6,7,8,9,0,
1,2,3));
return 0;
}
/* Note: using PP_NARG() without arguments would violate 6.10.3p4 of ISO C99. */ |
Partager