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

Function object for performing addition. Effectively calls operator+ on two instances of type T.


The standard library provides a specialization of std::plus 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 sum 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 sum of lhs and rhs.


lhs, rhs - values to sum

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;

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