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Difference between revisions of "cpp/utility/functional/negate"

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< cpp‎ | utility‎ | functional
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{{cpp/title|negate}}
 
{{cpp/title|negate}}
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{{ddcl list header | functional }}
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{{dcl header|functional}}
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{{dcl|until=c++14|
 
template< class T >
 
template< class T >
 
struct negate;
 
struct negate;
 
}}
 
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{{dcl|since=c++14|
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template< class T {{=}} void >
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struct negate;
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{{dcl end}}
  
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Function object for performing negation.
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Function object for performing negation. Effectively calls {{c|operator-}} on an instance of type {{tt|T}}.
  
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===Member types===
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===Specializations===
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{{tdcl list hitem | type | definition }}
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The standard library provides a specialization of {{tt|std::negate}} when {{tt|T}} is not specified, which leaves the parameter types and return type to be deduced.
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{{dsc inc|cpp/utility/functional/dsc negate_void}}
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{{cpp/utility/functional/member types|result=T|arg1=T}}
  
 
===Member functions===
 
===Member functions===
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{{dsc begin}}
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{{dcl list mem fun | cpp/utility/functional/negate/operator() | Returns the negation of its argument}}
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{{dsc mem fun|operator()|nolink=true|returns the negation of the argument}}
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{{member|{{small|std::negate::}}operator()|2=
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{{dcla|constexpr=c++14|1=
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T operator()( const T& arg ) const;
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Returns the negation of {{c|arg}}.
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===Parameters===
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{{par begin}}
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{{par|arg|value to compute negation 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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{{cpp/impldef exception}}
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===Possible implementation===
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{{eq fun|1=
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constexpr T operator()(const T& arg) const
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{
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    return -arg;
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}
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}}
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Latest revision as of 21:06, 13 July 2024

 
C++
 
Utilities library
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Identity function object
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Transparent operator wrappers
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Old binders and adaptors
(until C++17*)
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(until C++17*)  
(until C++17*)
(until C++17*)(until C++17*)(until C++17*)(until C++17*)
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(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 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.

Contents

[edit] 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.

(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) 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)

[edit] Member functions

operator()
 returns the negation of the argument
(public member function)

std::negate::operator()

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

Returns the negation of arg.

Parameters

arg - value to compute negation of

Return value

The result of -arg.

[edit] Exceptions

May throw implementation-defined exceptions.

Possible implementation

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