Initialising specific elements of a static const array in C++

Question

I have some C that I need to convert to C++.

It does something like this:

enum
{
   ELEM0,
   ELEM1,
   ELEM2,
   ELEM3,
   ELEM4,
   MAX_ELEMS
} 

#define LEN 16

static const char lut[MAX_ELEMS][LEN] =
{
    [ELEM2] = "Two",
    [ELEM3] = "Three",
    [ELEM1] = "One",
    [ELEM4] = "Four",
    [ELEM0] = "Zero"
}

In practice I have hundreds of elements without any order in the array. I need to guarantee that the entry in the array ties up the enumeration to the appropriate text.

Is it possible to initialise an array using positional parameters like this in -std=gnu++11?

Answer 1

No. Per gcc documentation, Designated Initializers do not exists in GNU C++.

In ISO C99 you can give the elements in any order, specifying the array indices or structure field names they apply to, and GNU C allows this as an extension in C89 mode as well. This extension is not implemented in GNU C++.

Doesn't this solve you problem (although it's run-time):

static const std::map<int, std::string> lut =
{
    std::make_pair(ELEM2, "Two"),
    std::make_pair(ELEM3, "Three"),
    std::make_pair(ELEM1, "One"),
};