std:: plus<void>

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C++
Utilities library
General utilities
Relational operators (deprecated in C++20)
Function objects
Function invocation
(C++17) (C++23)
Identity function object
(C++20)
Old binders and adaptors
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( until C++17* )
( until C++17* ) ( until C++17* ) ( until C++17* ) ( until C++17* )
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Defined in header <functional>
template <>
class plus < void > ;
(since C++14)

std:: plus < void > is a specialization of std::plus with parameter and return type deduced.

Member types

Type Definition
is_transparent unspecified

Member functions

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

std::plus<void>:: operator()

template < class T, class U >

constexpr auto operator ( ) ( T && lhs, U && rhs ) const

- > decltype ( std:: forward < T > ( lhs ) + std:: forward < U > ( rhs ) ) ;

Returns the sum of lhs and rhs .

Parameters

lhs, rhs - values to sum

Return value

std:: forward < T > ( lhs ) + std:: forward < U > ( rhs ) .

Example

Run this code 
#include <functional>
#include <iostream>
 
int main()
{
    auto string_plus = std::plus<void>{}; // “void” can be omitted
    std::string a = "Hello ";
    const char* b = "world";
    std::cout << string_plus(a, b) << '\n';
}

Output: 

Hello world
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