Namespaces
Variants
Views
Actions

std::byte

From cppreference.com
< cpp‎ | types
 
 
Utilities library
General utilities
Relational operators (deprecated in C++20)
Integer comparison functions
(C++20)(C++20)(C++20)
(C++20)
Swap and type operations
(C++14)
(C++11)
(C++11)
(C++11)
(C++17)
Common vocabulary types
(C++11)
(C++17)
(C++17)
(C++17)
(C++11)
(C++17)

Elementary string conversions
(C++17)
(C++17)
Stacktrace
 
Type support
Basic types
Fundamental types
Fixed width integer types (C++11)
byte
(C++17)
Numeric limits
C numeric limits interface
Runtime type information
Type traits
Type categories
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Type properties
(C++11)
(C++11)
(C++14)
(C++11)
(C++11)(until C++20)
(C++11)(deprecated in C++20)
(C++11)
Type trait constants
Metafunctions
(C++17)
Constant evaluation context
Supported operations
Relationships and property queries
Type modifications
(C++11)(C++11)(C++11)
Type transformations
(C++11)
(C++11)
(C++17)
(C++11)(until C++20)(C++17)
 
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.

Contents

[edit] 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));

[edit] 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.

[edit] 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