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Difference between revisions of "cpp/utility/functional/logical not"

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{{cpp/title|logical_not}}
 
{{cpp/title|logical_not}}
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template< class T >
 
template< class T >
 
struct logical_not;
 
struct logical_not;
 
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{{dcl|since=c++14|
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template< class T {{=}} void >
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struct logical_not;
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Function object for performing logical negations.
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Function object for performing logical NOT (logical negation). Effectively calls {{c|operator!}} for type {{tt|T}}.
  
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===Member types===
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===Specializations===
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The standard library provides a specialization of {{tt|std::logical_not}} when {{tt|T}} is not specified, which leaves the parameter types and return type to be deduced.
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===Member functions===
 
===Member functions===
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{{dcl list mem fun | cpp/utility/functional/logical_not/operator() | Returns the logical negation of its argument}}
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{{dsc mem fun|operator()|nolink=true|returns the logical NOT of the argument}}
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bool operator()( const T& arg ) const;
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Returns the logical NOT of {{c|arg}}.
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===Parameters===
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{{par begin}}
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{{par|arg|value to compute logical NOT of}}
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{{par end}}
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===Return value===
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The result of {{c|!arg}}.
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===Possible implementation===
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{{eq fun|1=
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constexpr // since C++14
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bool operator()(const T& arg) const
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{
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    return !arg;
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Latest revision as of 21:17, 13 July 2024

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

Function object for performing logical NOT (logical negation). Effectively calls operator! for type T.

Contents

[edit] Specializations

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

(C++14)
 function object implementing !x deducing parameter and return types
(class template specialization) [edit]
(since C++14)

[edit] Member types

Type Definition
result_type (deprecated in C++17)(removed in C++20) bool
argument_type (deprecated in C++17)(removed in C++20) T

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

(until C++11)

[edit] Member functions

operator()
 returns the logical NOT of the argument
(public member function)

std::logical_not::operator()

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

Returns the logical NOT of arg.

Parameters

arg - value to compute logical NOT of

Return value

The result of !arg.

[edit] Exceptions

May throw implementation-defined exceptions.

Possible implementation

constexpr // since C++14
bool operator()(const T& arg) const 
{
    return !arg;
}
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