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std::logical_not<void>

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Defined in header <functional>
template<>
class logical_not<void>;
(since C++14)

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

Contents

[edit] Member types

Member type Definition
is_transparent /* unspecified */

[edit] Member functions

operator()
applies operator! to its argument
(public member function)

std::logical_not<>::operator()

template< class T >

constexpr auto operator()( T&& arg ) const

  -> decltype(!std::forward<T>(arg));

Returns the result of !arg.

Parameters

arg - value to apply logical NOT to

Return value

The result of !arg.

[edit] Notes

The member type is_transparent indicates to the caller that this function object is a transparent function object: it accepts arguments of arbitrary types and uses perfect forwarding, which avoids unnecessary copying and conversion when the function object is used in heterogeneous context, or with rvalue arguments. In particular, template functions such as std::set::find and std::set::lower_bound make use of this member type on their Compare types.

[edit] Example