Defined in header <functional>
template< class T >
struct bit_or;
(until C++14)
template< class T = void >
struct bit_or;
(since C++14)

Function object for performing bitwise OR. Effectively calls operator| on type T.


The standard library provides a specialization of std::bit_or when T is not specified, which leaves the parameter types and return type to be deduced.

function object implementing x | y deducing argument and return types
(class template specialization)
(since C++14)

Member types

Type Definition
result_type (deprecated in C++17)(removed in C++20) T
first_argument_type (deprecated in C++17)(removed in C++20) T
second_argument_type (deprecated in C++17)(removed in C++20) T

These member types are obtained via publicly inheriting std::binary_function<T, T, T>.

(until C++11)

Member functions

returns the result of bitwise OR of two arguments
(public member function)


T operator()( const T& lhs, const T& rhs ) const;
(until C++14)
constexpr T operator()( const T& lhs, const T& rhs ) const;
(since C++14)

Returns the result of bitwise OR of lhs and rhs.


lhs, rhs - values to compute bitwise OR of

Return value

The result of lhs | rhs.


May throw implementation-defined exceptions.

Possible implementation

constexpr T operator()(const T &lhs, const T &rhs) const
    return lhs | rhs;

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 660 C++98 function objects for bitwise operations are missing added

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