C/C++ useful macros

gistfile1.cpp

#define CONCATENATE(arg1, arg2)  arg1##arg2

#define IN_NARG(...) IN_NARG_(__VA_ARGS__, IN_RSEQ_N())
#define IN_NARG_(...) IN_ARG_N(__VA_ARGS__) 
#define IN_ARG_N(_1,  _2,  _3,  _4,  _5,  _6,  _7,  _8,  _9, N, ...) N
#define IN_RSEQ_N() 9,  8,  7,  6,  5,  4,  3,  2,  1,  0

#define IN_1(x, v, ...) ((v) == (x))
#define IN_2(x, v, ...) ((v) == (x)) || IN_1(x, __VA_ARGS__)
#define IN_3(x, v, ...) ((v) == (x)) || IN_2(x, __VA_ARGS__)
#define IN_4(x, v, ...) ((v) == (x)) || IN_3(x, __VA_ARGS__)
#define IN_5(x, v, ...) ((v) == (x)) || IN_4(x, __VA_ARGS__)
#define IN_6(x, v, ...) ((v) == (x)) || IN_5(x, __VA_ARGS__)
#define IN_7(x, v, ...) ((v) == (x)) || IN_6(x, __VA_ARGS__)
#define IN_8(x, v, ...) ((v) == (x)) || IN_7(x, __VA_ARGS__)
#define IN_9(x, v, ...) ((v) == (x)) || IN_8(x, __VA_ARGS__)
#define IN_10(x, v, ...) ((v) == (x)) || IN_9(x, __VA_ARGS__)

#define IN_(N, x, v, ...) CONCATENATE(IN_, N)(x, v, __VA_ARGS__)
#define IN(x, n, ...) IN_(IN_NARG(n, __VA_ARGS__), x, n, __VA_ARGS__)

#define FOREACH(item, array) \
    for(int keep=1, \
            count=0,\
            size=sizeof (array)/sizeof *(array); \
        count != size; \
        keep=1, count++) \
      for(item = (array)+count; keep; keep = !keep)