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

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template< class T >
 
template< class T >
 
struct logical_not;
 
struct logical_not;
 
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template< class T {{=}} void >
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struct logical_not;
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Function object for performing logical NOT (logical negation). Effectively calls {{c|operator!}} for type {{tt|T}}.
 
Function object for performing logical NOT (logical negation). Effectively calls {{c|operator!}} for type {{tt|T}}.
  
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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===
 
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bool operator()( const T& arg ) const;
 
bool operator()( const T& arg ) const;
 
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Returns the logical NOT of {{tt|arg}}.
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Returns the logical NOT of {{c|arg}}.
  
 
===Parameters===
 
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The result of {{c|!arg}}.
 
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bool operator()(const T &arg) const  
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Latest revision as of 21:17, 13 July 2024

 
C++
 
Utilities library
General utilities
Relational operators (deprecated in C++20)
 
Function objects
Function invocation
(C++17)(C++23)
Identity function object
(C++20)
Transparent operator wrappers
(C++14)
(C++14)
(C++14)
(C++14)  
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)

Old binders and adaptors
(until C++17*)
(until C++17*)
(until C++17*)
(until C++17*)
(until C++17*)  
(until C++17*)
(until C++17*)(until C++17*)(until C++17*)(until C++17*)
(until C++20*)
(until C++20*)
(until C++17*)(until C++17*)
(until C++17*)(until C++17*)

(until C++17*)
(until C++17*)(until C++17*)(until C++17*)(until C++17*)
(until C++20*)
(until C++20*)
 
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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