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std::negate

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

Function object for performing negation. Effectively calls operator- on an instance of type T.

Specializations

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

negate<void>

(C++14)

function object implementing -x 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`
`argument_type` (deprecated in C++17)(removed in C++20)	`T`

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

(until C++11)

Member functions

operator()

returns the negation of the argument
(public member function)

std::negate::operator()

T operator()( const T& arg ) const;		(until C++14)
constexpr T operator()( const T& arg ) const;		(since C++14)

Returns the negation of arg.

Parameters

arg

value to compute negation of

Return value

The result of -arg.

Exceptions

May throw implementation-defined exceptions.

Possible implementation

constexpr T operator()(const T &arg) const 
{
    return -arg;
}

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https://en.cppreference.com/w/cpp/utility/functional/negate