# std::plus

From cppreference.com
< cpp‎ | utility‎ | functional

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`.

### Specializations

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.

plus<void> | 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) | `T`
`first_argument_type`(deprecated in C++17) | `T`
`second_argument_type`(deprecated in C++17) | `T`

(until C++20)

### Member functions

operator() | returns the sum of two arguments (public member function)

## std::plus::operator()

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`.

### Parameters

lhs, rhs | - | values to sum

### Return value

The result of lhs + rhs.

### Exceptions

(none)

### Possible implementation

    constexpr T operator()(const T &lhs, const T &rhs) const
    {
        return lhs + rhs;
    }

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