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Defined in header <cstddef> | ||
enumclass byte:unsignedchar{}; | (since C++17) | |
std::byte is a distinct type that implements the concept of byte as specified in the C++ language definition.
Likeunsignedchar, it can be used to access raw memory occupied by other objects (object representation), but unlikeunsignedchar, it is not a character type and is not an arithmetic type.std::byte models a mere collection of bits, supporting only bitshift operations with an integer, and bitwise and comparison operations with anotherstd::byte.
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template<class IntegerType> constexpr IntegerType to_integer( std::byte b)noexcept; | (since C++17) | |
Equivalent to:return IntegerType(b);This overload participates in overload resolution only ifstd::is_integral_v<IntegerType> istrue.
template<class IntegerType> constexpr std::byte& operator<<=( std::byte& b, IntegerType shift)noexcept; | (1) | (since C++17) |
template<class IntegerType> constexpr std::byte& operator>>=( std::byte& b, IntegerType shift)noexcept; | (2) | (since C++17) |
This overload participates in overload resolution only ifstd::is_integral_v<IntegerType> istrue.
template<class IntegerType> constexpr std::byte operator<<( std::byte b, IntegerType shift)noexcept; | (1) | (since C++17) |
template<class IntegerType> constexpr std::byte operator>>( std::byte b, IntegerType shift)noexcept; | (2) | (since C++17) |
This overload participates in overload resolution only ifstd::is_integral_v<IntegerType> istrue.
constexpr std::byte& operator|=( std::byte& l, std::byte r)noexcept; | (1) | (since C++17) |
constexpr std::byte& operator&=( std::byte& l, std::byte r)noexcept; | (2) | (since C++17) |
constexpr std::byte& operator^=( std::byte& l, std::byte r)noexcept; | (3) | (since C++17) |
constexpr std::byte operator|( std::byte l, std::byte r)noexcept; | (1) | (since C++17) |
constexpr std::byte operator&( std::byte l, std::byte r)noexcept; | (2) | (since C++17) |
constexpr std::byte operator^( std::byte l, std::byte r)noexcept; | (3) | (since C++17) |
constexpr std::byte operator~( std::byte b)noexcept; | (4) | (since C++17) |
A numeric valuen can be converted to a byte value usingstd::byte{n}, due to C++17relaxed enum class initialization rules.
A byte can be converted to a numeric value (such as to produce an integer hash of an object) the usual way with anexplicit conversion or alternatively withstd::to_integer.
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_byte | 201603L | (C++17) | std::byte |
#include <bitset>#include <cassert>#include <cstddef>#include <iostream>#include <utility> std::ostream& operator<<(std::ostream& os, std::byte b){return os<<std::bitset<8>(std::to_integer<int>(b));} int main(){// std::byte y = 1; // Error: cannot convert int to byte. std::byte y{1};// OK // if (y == 13) {} // Error: cannot be compared.if(y== std::byte{13}){}// OK, bytes are comparable int arr[]{1,2,3};// int c = a[y]; // Error: array subscript is not an integer[[maybe_unused]]int i= arr[std::to_integer<int>(y)];// OK[[maybe_unused]]int j= arr[std::to_underlying(y)];// OK auto to_int=[](std::byte b){return std::to_integer<int>(b);}; std::byte b{42};assert(to_int(b)==0b00101010);std::cout<< b<<'\n'; // b *= 2; // Error: b is not of arithmetic type b<<=1;assert(to_int(b)==0b01010100); b>>=1;assert(to_int(b)==0b00101010); assert(to_int(b<<1)==0b01010100);assert(to_int(b>>1)==0b00010101); b|= std::byte{0b11110000};assert(to_int(b)==0b11111010); b&= std::byte{0b11110000};assert(to_int(b)==0b11110000); b^= std::byte{0b11111111};assert(to_int(b)==0b00001111);}
Output:
00101010
