std::byte

< cpp‎ | types

Defined in header `<cstddef>`
enum class byte : unsigned char {} ;		(since C++17)

std::byte is a distinct type that implements the concept of byte as specified in the C++ language definition.

Like char and unsigned char, it can be used to access raw memory occupied by other objects (object representation), but unlike those types, it is not a character type and is not an arithmetic type. A byte is only a collection of bits, and the only operators defined for it are the bitwise ones.

Non-member functions

std::to_integer

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 if std::is_integral_v<IntegerType> is true.

std::operator<<=,operator>>=

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)

1) Equivalent to: return b = b << shift; This overload participates in overload resolution only if std::is_integral_v<IntegerType> is true.

2) Equivalent to: return b = b >> shift;

This overload participates in overload resolution only if std::is_integral_v<IntegerType> is true.

std::operator<<,operator>>

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)

1) Equivalent to: return std::byte(static_cast<unsigned int>(b) << shift); This overload participates in overload resolution only if std::is_integral_v<IntegerType> is true.

2) Equivalent to: return std::byte(static_cast<unsigned int>(b) >> shift);

This overload participates in overload resolution only if std::is_integral_v<IntegerType> is true.

std::operator|=,operator&=,operator^=

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)

1) Equivalent to: return l = l | r;.

2) Equivalent to: return l = l & r;.

3) Equivalent to: return l = l ^ r;.

std::operator|,operator&,operator^,operator~

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)

1) Equivalent to: return std::byte(static_cast<unsigned int>(l) | static_cast<unsigned int>(r));.

2) Equivalent to: return std::byte(static_cast<unsigned int>(l) & static_cast<unsigned int>(r));.

3) Equivalent to: return std::byte(static_cast<unsigned int>(l) ^ static_cast<unsigned int>(r));.

4) Equivalent to: return std::byte(~static_cast<unsigned int>(b));

Notes

A numeric value n can be converted to a byte value using std::byte{n}, due to C++17 relaxed enum class initialization rules.

A byte can be converted to a numeric value (such as to produce an integer hash of an object) using std::to_integer.

Example

#include <iostream>
#include <cstddef>
 
int main()
{
    std::byte b{42};
    std::cout << std::to_integer<int>(b) << "\n";
 
    // b *= 2 compilation error
    b <<= 1;
    std::cout << std::to_integer<int>(b) << "\n";
}

Output:

42
84