std::endian

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

Indicates theendianness of allscalar types:

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

Corner case platforms are also supported:

If all scalar types havesizeof equal to1, endianness does not matter and all three values,std::endian::little,std::endian::big, andstd::endian::native are the same.
If the platform uses mixed endian,std::endian::native equals neitherstd::endian::big norstd::endian::little.

[edit]Possible implementation

enumclass 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};

[edit]Notes

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

[edit]Example

Run this code

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