[Technology] Generic selection in C11? Pretty neat

http://www.robertgamble.net/2012/01/c11-generic-selections.html

#define acos(X) _Generic((X), \

    long double complex: cacosl, \

    double complex: cacos, \

    float complex: cacosf, \

    long double: acosl, \

    float: acosf, \

    default: acos \

    )(X)

Also, need to remember that character constants are ints, and not char.

Also, __auto_type is pretty cool:

     #define max(a,b) \
       ({ __auto_type _a = (a); \
           __auto_type _b = (b); \
         _a > _b ? _a : _b; })