std:: endian

Indicates the endianness of all scalar types :

• If all scalar types are little-endian, std :: endian :: native equals std :: endian :: little .
• If all scalar types are big-endian, std :: endian :: native equals std :: endian :: big .

Corner case platforms are also supported:

• If all scalar types have sizeof equal to 1 , endianness does not matter and all three values, std :: endian :: little , std :: endian :: big , and std :: endian :: native are the same.
• If the platform uses mixed endian, std :: endian :: native equals neither std :: endian :: big nor std :: endian :: little .

Possible implementation

enum class endian
{
#if defined(_MSC_VER) && !defined(__clang__)
    little = 0,
    big    = 1,
    native = little
#else
    little = __ORDER_LITTLE_ENDIAN__,
    big    = __ORDER_BIG_ENDIAN__,
    native = __BYTE_ORDER__
#endif
};

Notes

Example

#include <bit>
#include <iostream>
 
int main()
{
    if constexpr (std::endian::native == std::endian::big)
        std::cout << "big-endian\n";
    else if constexpr (std::endian::native == std::endian::little)
        std::cout << "little-endian\n";
    else
        std::cout << "mixed-endian\n";
}

mixed-endian

See also