How to define endian enum class waiting for C++20?

Question

Considering the possible implementation here:

enum class endian
{
#ifdef _WIN32
    little = 0,
    big    = 1,
    native = little
#else
    little = __ORDER_LITTLE_ENDIAN__,
    big    = __ORDER_BIG_ENDIAN__,
    native = __BYTE_ORDER__
#endif
};

Is it sure that

__ORDER_LITTLE_ENDIAN__, __ORDER_BIG_ENDIAN__, __BYTE_ORDER__

are defined in other platforms than WIN32?

Before C++20 is released, is it possible to define such an enum for endianness? Otherwise, how to do it properly?

You may want to take a look at [boost endian](https://www.boost.org/doc/libs/1_68_0/libs/endian/doc/conversion.html) — user7860670, Nov 28 '18 at 13:43
Is it possible? Sure, but I'm seeing a similar enum in [boost](https://www.boost.org/doc/libs/1_68_0/libs/endian/doc/conversion.html) so maybe that would do? — Borgleader, Nov 28 '18 at 13:43
The "possible implementation" is not a standardized or otherwise official way of implementing the enumeration. Instead it depends a *lot* on the compiler used and its corresponding standard library parts. What is shown is only a *possibility*, an *example* without any basis on real implementations. — Some programmer dude, Nov 28 '18 at 13:43
for gcc see here: https://gcc.gnu.org/onlinedocs/cpp/Common-Predefined-Macros.html — 463035818_is_not_a_number, Nov 28 '18 at 13:43
This is going to compiler dependent. If you need something poratable use [Boost.Endian](https://www.boost.org/doc/libs/1_63_0/libs/endian/doc/index.html) — NathanOliver, Nov 28 '18 at 13:44
@user463035818 but I am wondering if those macro are garanteed to be defined. — FlashMcQueen, Nov 28 '18 at 13:44
They are not. `std::endian` is the guaranteed interface. However your implementation implements it is up to them. — NathanOliver, Nov 28 '18 at 13:46
the macros used in the example are those defined for gcc. For other compilers you have to check their documentation — 463035818_is_not_a_number, Nov 28 '18 at 13:59

How to define endian enum class waiting for C++20?

0 Answers0