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Difference between revisions of "cpp/types/endian"

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< cpp‎ | types
m (→‎See also: + byteswap)
m (→‎Notes: + feature test macro)
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===Notes===
 +
{{feature test macro|__cpp_lib_endian}}
  
 
===Example===
 
===Example===

Revision as of 15:08, 31 January 2022

 
C++
 
Numerics library
Common mathematical functions
Mathematical special functions (C++17)
Mathematical constants (C++20)
Basic linear algebra algorithms (C++26)
Floating-point environment (C++11)
Complex numbers
Numeric array (valarray)
Pseudo-random number generation
Factor operations
(C++17)
(C++17)
Interpolations
(C++20)
(C++20)
Saturation arithmetic
(C++26)
(C++26)
(C++26)
(C++26)
(C++26)

Generic numeric operations
Bit operations
(C++20)    
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++23)
endian
(C++20)
 
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.

Contents

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 Value Std Feature
__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

(C++23)
 reverses the bytes in the given integer value
(function template) [edit]
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