std::endian

 

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Defined in header <bit>
enum class endian {     little = /*implementation-defined*/,     big    = /*implementation-defined*/,     native = /*implementation-defined*/, };		(since C++20)

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

Feature-test macro	Value	Std	Feature
__cpp_lib_endian	201907L	(C++20)	std::endian

Example

Run this code

#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";
}

Possible output:

mixed-endian

See also

byteswap (C++23)

reverses the bytes in the given integer value (function template)