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byteswap (C++23) | ||||
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| Rotating | ||||
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Defined in header <bit> | ||
template<class T> constexpr T byteswap( T n)noexcept; | (since C++23) | |
Reverses the bytes in the given integer valuen.
std::byteswap participates in overload resolution only ifT satisfiesintegral, i.e.,T is an integer type. The program is ill-formed ifT has padding bits.
Contents |
| n | - | integer value |
An integer value of typeT whose object representation comprises the bytes of that ofn in reversed order.
This function is useful for processing data of different endianness.
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_byteswap | 202110L | (C++23) | std::byteswap |
template<std::integral T>constexpr T byteswap(T value)noexcept{ static_assert(std::has_unique_object_representations_v<T>,"T may not have padding bits");auto value_representation=std::bit_cast<std::array<std::byte, sizeof(T)>>(value); std::ranges::reverse(value_representation);returnstd::bit_cast<T>(value_representation);} |
#include <bit>#include <concepts>#include <cstdint>#include <iomanip>#include <iostream> template<std::integral T>void dump(T v,char term='\n'){std::cout<<std::hex<<std::uppercase<<std::setfill('0')<<std::setw(sizeof(T)*2)<< v<<" : ";for(std::size_t i{}; i!= sizeof(T);++i, v>>=8)std::cout<<std::setw(2)<<static_cast<unsigned>(T(0xFF)& v)<<' ';std::cout<<std::dec<< term;} int main(){ static_assert(std::byteswap('a')=='a'); std::cout<<"byteswap for U16:\n";constexprauto x=std::uint16_t(0xCAFE); dump(x); dump(std::byteswap(x)); std::cout<<"\nbyteswap for U32:\n";constexprauto y=std::uint32_t(0xDEADBEEFu); dump(y); dump(std::byteswap(y)); std::cout<<"\nbyteswap for U64:\n";constexprauto z=std::uint64_t{0x0123456789ABCDEFull}; dump(z); dump(std::byteswap(z));}
Possible output:
byteswap for U16:CAFE : FE CAFECA : CA FE byteswap for U32:DEADBEEF : EF BE AD DEEFBEADDE : DE AD BE EF byteswap for U64:0123456789ABCDEF : EF CD AB 89 67 45 23 01EFCDAB8967452301 : 01 23 45 67 89 AB CD EF
(C++20) | indicates the endianness of scalar types (enum)[edit] |
(C++20) | computes the result of bitwise left-rotation (function template)[edit] |
(C++20) | computes the result of bitwise right-rotation (function template)[edit] |
