macro to define a struct in c or c++ -

macro to define a struct in c or c++ -

is possible define struct variable size of array. this:

#define char_array(max_length) struct char_array_#max_length{char data[max_length]; int length;};

so above macro, define different info types follows.

struct data{ char_array(4) a; char_array(8) b; };

due special requirements of existing code, plain old type defined "struct" required, no utilize of std::array, vector, etc. in particular, pointer not accepted our legacy code has requirement plain old type, assign or re-create can handled.

yes it’s possible that. don’t need name struct @ all, makes macro simpler:

#define char_array(max_length) struct {char data[max_length]; int length;}

(usage in example.)

however, i’m still not exclusively clear purpose of macro, since re-implements, badly, existing functionality. @ to the lowest degree should utilize template instead of macro generate type you:

template <std::size_t n> struct char_array { char data[n]; std::size_t length; };

and create element type generic:

template <typename t, std::size_t n> struct array { t data[n]; std::size_t length; };

… , it’s becoming blindingly obvious bad re-implementation of std::array, , there no benefit in not using latter.

c++ c macros preprocessor