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Difference between revisions of "Template:cpp/types/traits/is"

From cppreference.com
m (→‎Helper variable template: bump wrapping cutoff value to 25.)
m (→‎Helper variable template: -`inline`: CWG2387)
 
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{{ddcl|header=type_traits|since={{cpp/std max|c++11|{{{std|c++11}}}}}|deprecated ={{#if:{{{deprecated|}}}|{{cpp/std max|c++11|{{{deprecated|}}}}}}}|removed={{#if:{{{removed|}}}|{{cpp/std max|c++11|{{{removed|}}}}}}}|1=
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template< class T >
 
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{{tt|std::{{{1|}}}}} is a {{named req|UnaryTypeTrait}}.
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{{{description|{{error|no description given}}}}}
  
 
{{#ifeq:{{cpp/std max|c++14|{{{std|}}}}}|c++14|{{cpp/types/nospec|v}}|{{cpp/types/nospec|pv}}}}
 
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===Helper variable template===
 
===Helper variable template===
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{{ddcl|since={{cpp/std max|c++17|{{{std|c++17}}}}}|deprecated={{#if:{{{deprecated|}}}|{{#ifeq:{{cpp/std max|c++17|{{{deprecated|}}}}}|c++17|yes|{{{deprecated|}}}}}}}|removed={{#if:{{{removed|}}}|{{cpp/std max|c++17|{{{removed|}}}}}}}|1=
 
template< class T >
 
template< class T >
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inline constexpr bool {{{1|}}}_v {{#ifeq:{{#expr:{{#len:{{{1|}}}}}>25}}|0|= {{{1|}}}|=
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constexpr bool {{{1|}}}_v {{#ifeq:{{#expr:{{#len:{{{1|}}}}}>25}}|0|= {{{1|}}}|=
 
     {{{1|}}}}}<T>::value;
 
     {{{1|}}}}}<T>::value;
 
}}
 
}}
  
 
{{cpp/types/integral_constant/inherit|{{{inherit_desc|}}}}}
 
{{cpp/types/integral_constant/inherit|{{{inherit_desc|}}}}}

Latest revision as of 04:44, 24 September 2024

 
C++
 
Metaprogramming library
Type traits
Type categories
(C++11)
(C++14)  
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)  
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Type properties
(C++11)
(C++11)
(C++11)
(C++11)
(C++14)
(C++11)
(C++17)
(C++23)
(C++11)
(C++11)
(C++11)
(C++11)(until C++20*)
(C++11)(deprecated in C++20)
(C++11)
(C++11)
(C++20)
(C++20)
(C++23)
(C++17)
Type trait constants
(C++11)(C++17)(C++11)(C++11)
Metafunctions
(C++17)
(C++17)
(C++17)
Supported operations
Relationships and property queries
Type modifications
(C++11)(C++11)(C++11)
(C++11)(C++11)(C++11)
(C++11)
(C++11)
Type transformations
(C++11)(deprecated in C++23)
(C++11)(deprecated in C++23)
(C++11)
(C++20)
(C++11)
(C++17)

(C++11)
(C++11)
(C++20)
(C++11)
(C++11)(until C++20*)(C++17)
(C++20)
Compile-time rational arithmetic
Compile-time integer sequences
(C++14)
 
Defined in header <type_traits>
template< class T >
struct ;
 (since C++11)

std:: is a UnaryTypeTrait.

no description given

If the program adds specializations for std::is or std::is_v, the behavior is undefined.

Contents

[edit] Template parameters

T - a type to check

[edit] Helper variable template

template< class T >
constexpr bool _v =<T>::value;
 (since C++17)
[edit]

Inherited from std::integral_constant

Member constants

value
[static]
 true if , false otherwise
(public static member constant)

Member functions

operator bool
 converts the object to bool, returns value
(public member function)
operator()
(C++14)
 returns value
(public member function)

Member types

Type Definition
value_type bool
type std::integral_constant<bool, value>
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