NAME

std::endian - std::endian

Synopsis

Defined in header <bit>
enum class endian

{
little = /*implementation-defined*/, (since C++20)
big = /*implementation-defined*/,
native = /*implementation-defined*/

};

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

Notes

Feature-test macro: __cpp_lib_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:

little-endian

See also

byteswap reverses the bytes in the given integer value
(C++23) (function template)