std::is_assignable, std::is_trivially_assignable, std::is_nothrow_assignable

 

C++

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Requerimentos nomeados

Feature test macros (C++20)

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Ranges library(C++20)

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Especificações Técnicas

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Data e hora

Objetos de função

initializer_list (C++11)

bitset

hash (C++11)

Os operadores relacionais Original: Relational operators The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

rel_ops::operator!= rel_ops::operator> rel_ops::operator<= rel_ops::operator>=

Pares e tuplas Original: Pairs and tuples The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

pair

tuple (C++11)

piecewise_construct_t (C++11)

piecewise_construct (C++11)

Troque, avançar e avançar Original: Swap, forward and move The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

swap

forward (C++11)

move (C++11)

move_if_noexcept (C++11)

declval (C++11)

 

Apoio a tipos

Tipos básicos Original: Basic types The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
Tipos fundamentais
Tipos inteiros de largura fixos(C++11)
ptrdiff_t size_t max_align_t (C++11)	nullptr_t (C++11) offsetof NULL
Limites numéricos Original: Numeric limits The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
numeric_limits
C numérico limita interface
Informações de tipo de tempo de execução Original: Runtime type information The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
type_info type_index (C++11)	bad_typeid bad_cast
Características de tipo Original: Type traits The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
Principais categorias de tipo Original: Primary type categories The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_void (C++11) is_array (C++11) is_pointer (C++11) is_enum (C++11) is_union (C++11) is_class (C++11) is_function (C++11)	is_object (C++11) is_scalar (C++11) is_compound (C++11) is_integral (C++11) is_floating_point (C++11) is_fundamental (C++11) is_arithmetic (C++11)
is_reference (C++11)
is_lvalue_reference (C++11)
is_rvalue_reference (C++11)
is_member_pointer (C++11)
is_member_object_pointer (C++11)
is_member_function_pointer (C++11)

Propriedades de tipo Original: Type properties The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_const (C++11) is_volatile (C++11) is_pod (C++11) is_empty (C++11) is_polymorphic (C++11) is_abstract (C++11)	is_trivial (C++11) is_trivially_copyable (C++11) is_standard_layout (C++11) is_literal_type (C++11) is_signed (C++11) is_unsigned (C++11)

Operações apoiadas Original: Supported operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_constructibleis_trivially_constructibleis_nothrow_constructible (C++11)(C++11)(C++11)
is_default_constructibleis_trivially_default_constructibleis_nothrow_default_constructible (C++11)(C++11)(C++11)
is_copy_constructibleis_trivially_copy_constructibleis_nothrow_copy_constructible (C++11)(C++11)(C++11)
is_move_constructibleis_trivially_move_constructibleis_nothrow_move_constructible (C++11)(C++11)(C++11)
is_assignableis_trivially_assignableis_nothrow_assignable (C++11)(C++11)(C++11)
is_copy_assignableis_trivially_copy_assignableis_nothrow_copy_assignable (C++11)(C++11)(C++11)
is_move_assignableis_trivially_move_assignableis_nothrow_move_assignable (C++11)(C++11)(C++11)
is_destructibleis_trivially_destructibleis_nothrow_destructible (C++11)(C++11)(C++11)
has_virtual_destructor (C++11)
Relacionamentos e consultas de propriedade Original: Relationships and property queries The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_same (C++11) is_base_of (C++11) is_convertible (C++11)	alignment_of (C++11) rank (C++11) extent (C++11)
Tipo modificações Original: Type modifications The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
remove_cvremove_constremove_volatile (C++11)(C++11)(C++11) add_cvadd_constadd_volatile (C++11)(C++11)(C++11) make_signed (C++11) make_unsigned (C++11)	remove_reference (C++11) add_lvalue_referenceadd_rvalue_reference (C++11)(C++11) remove_pointer (C++11) add_pointer (C++11) remove_extent (C++11) remove_all_extents (C++11)
Transformações tipo Original: Type transformations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
aligned_storage (C++11) aligned_union (C++11) decay (C++11) enable_if (C++11)	conditional (C++11) common_type (C++11) underlying_type (C++11) result_of (C++11)
Digite constantes traço Original: Type trait constants The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
integral_constant (C++11)

 

Definido no cabeçalho <type_traits>
template<class T, class U > struct is_assignable;	(1)	(desde C++11)
template<class T, class U > struct is_trivially_assignable;	(2)	(desde C++11)
template<class T, class U > struct is_nothrow_assignable;	(3)	(desde C++11)

1)

Se o std::declval<T>()=std::declval<U>() expressão é bem-formado em contexto não avaliada, fornece o membro constante valuetrue igual. Para qualquer outro tipo, é valuefalse.

Original:

If the expression std::declval<T>()=std::declval<U>() is well-formed in unevaluated context, provides the member constant value equal true. For any other type, value is false.

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2)

mesmo que 1), mas a avaliação da expressão de atribuição não irá chamar qualquer operação que não é trivial.

Original:

same as 1), but evaluation of the assignment expression will not call any operation that is not trivial.

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3)

mesmo que 1), mas a avaliação da expressão de atribuição não irá chamar qualquer operação que não está noexcept.

Original:

same as 1), but the evaluation of the assignment expression will not call any operation that is not noexcept.

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Herdado de std::integral_constant

Member constants

value [estática]	true se T is assignable from U , false contrário Original: true if T is assignable from U , false otherwise The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (membro estático público constante)

Member functions

operator bool	converte o objeto em bool, retorna value Original: converts the object to bool, returns value The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (função pública membro)

Member types

Tipo Original: Type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.	Definition
value_type	bool
type	std::integral_constant<bool, value>

Exemplo

#include <iostream>#include <string>#include <type_traits>struct Ex1 {int n;};int main(){std::cout<<std::boolalpha<<"int is assignable from double? "<< std::is_assignable<int, double>::value<<'\n'<<"int& is nothrow assignable from double? "<< std::is_nothrow_assignable<int&, double>::value<<'\n'<<"string is assignable from double? "<< std::is_assignable<std::string, double>::value<<'\n'<<"Ex1& is trivially assignable from const Ex1&? "<< std::is_trivially_assignable<Ex1&, const Ex1&>::value<<'\n';}

Saída:

int is assignable from double? false int& is nothrow assignable from double? true string is assignable from double? true Ex1& is trivially assignable from const Ex1&? true

Veja também

is_copy_assignable is_trivially_copy_assignable is_nothrow_copy_assignable (C++11) (C++11) (C++11)	verifica se um tipo tem um operador de atribuição de cópia Original: checks if a type has a copy assignment operator The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (modelo de classe)
is_move_assignable is_trivially_move_assignable is_nothrow_move_assignable (C++11) (C++11) (C++11)	verifica se um tipo tem um operador de atribuição movimento Original: checks if a type has a move assignment operator The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (modelo de classe)