Yet another static array initialization in C++ -

i have following code in c++ (c++11 available)

typedef enum {     apple,    orange,    last, } fruits_t;  template <typename t, size_t size> char (&arraysizehelper( t (&)[size]))[size]; #define arraysize(parray) sizeof(arraysizehelper(parray))  static const char *lookup_table[] {    "apple",  // apple    "orange", // orange }; // fail compilation if lookup table missing static_assert(arraysize(lookup_table) == last, "update lookup table"); 

i want able change order in enumeration without changing initialisation list in lookup_table.

i have read initialization of normal array 1 default value , template need, not quite. struggled metaprogramming half day , still can not figure out how it.

the actual enumeration in code starts 0 , contains 20-30 entries. have considered hash table - hash function trivial, problem of initialization remains. have many - 5+ - lookup tables in code. worth struggle?

p.s. after couple of answers around switch construct let me show chunk of real code. 1 example.

typedef enum {     events_statistics_collector_pool_timeout            ,     events_statistics_collector_pool_failed             ,     events_statistics_collector_sent_to_pipeline        ,      // 50 entries      events_statisitcs_last                              , } events_statistics_t;  uint64_t events_statistics[events_statisitcs_last]; const char *event_statistics_names[] = {     "collector_pool_timeout         ",     "collector_pool_failed          ",     "collector_sent_to_pipeline     ",     // , on ... };  static inline void events_statistics_bump_counter(events_statistics_t counter) {     events_statistics[counter]++; }  // actual function generic 1 prints arbitrary pairs // 1 gives idea void print_statistics() {     int col = 0;     static const int columns = 3;     printf("\n");     (int = 0;i < events_statisitcs_last;i++)     {         printf("%-30s %9lu", event_statistics_names[i], events_statistics[i]);         col++;         if ((col % columns) == 0)             printf("\n");         else             printf("%4s", "");     }     if ((col % columns) != 0)         printf("\n"); } 

p.s.2 wanted in previous p.s. "switch" gives freedom compiler. want ensure lookup simple table , not double indexed array or if/else branches

p.s.3 here example of initialised array. array contains hooks , of extreme importance call correct function.

typedef struct {     const int id;     const events_process_t processor;     uint64_t counter; } events_process_table_t;  static events_process_table_t events_processors[event_id_last] = {         {event_id_open          , (events_process_t)events_process_open             },         {event_id_openat        , (events_process_t)events_process_open             },         // , on 30 lines }; static_assert(arraysize(events_processors) == event_id_last, "update table of events processors");  void some_code(int event_id) {         events_process_table_t *table = &events_processors[event_id];         if (event_id == table->id)         {               // looks alright , can use table->processor               // .....          } } 

i think efficient way handle situation function maps enum values corresponding c-string:

enum class fruits { apple, orange, last };  char const* show(fruits x) {     switch (x) {         case fruits::apple: return "apple";         case fruits::orange: return "orange";         case fruits::last: return "last";     }     assert(false);     return nullptr; } 

live demo

at point, if forget define fruits::last's string in show, compilers warn like:

main.cpp: in function 'const char* show(fruits)':

main.cpp:7:12: warning: enumeration value 'last' not handled in switch [-wswitch]

 switch (x) { 

live demo

which if compile -werror prevent compilation.