Espaços nominais
Variantes
Acções

std::integral_constant

Da cppreference.com
< cpp‎ | types

 
 
Biblioteca de utilitários
Digite apoio (basic types, RTTI, type traits)
Gerenciamento de memória dinâmica
De tratamento de erros
Utilidades do programa
Variadic funções
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)
 
Digite apoio
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)
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.
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)
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_constructible
is_trivially_constructible
is_nothrow_constructible
(C++11)
(C++11)
(C++11)
is_default_constructible
is_trivially_default_constructible
is_nothrow_default_constructible
(C++11)
(C++11)
(C++11)
is_copy_constructible
is_trivially_copy_constructible
is_nothrow_copy_constructible
(C++11)
(C++11)
(C++11)
is_move_constructible
is_trivially_move_constructible
is_nothrow_move_constructible
(C++11)
(C++11)
(C++11)
is_assignable
is_trivially_assignable
is_nothrow_assignable
(C++11)
(C++11)
(C++11)
is_copy_assignable
is_trivially_copy_assignable
is_nothrow_copy_assignable
(C++11)
(C++11)
(C++11)
is_move_assignable
is_trivially_move_assignable
is_nothrow_move_assignable
(C++11)
(C++11)
(C++11)
is_destructible
is_trivially_destructible
is_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_cv
remove_const
remove_volatile
(C++11)
(C++11)
(C++11)
add_cv
add_const
add_volatile
(C++11)
(C++11)
(C++11)
make_signed(C++11)
make_unsigned(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)
 
Defined in header <type_traits>
template< class T, T v >
struct integral_constant;
(a partir do C++ 11)
std::integral_constant envolve uma constante estática do tipo especificado. É a classe base para o C + + características de tipo.
Original:
std::integral_constant wraps a static constant of specified type. It is the base class for the C++ type traits.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Duas especializações para o bool tipo são fornecidos:
Original:
Two specializations for the type bool are provided:
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Defined in header <type_traits>
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
true_type std::integral_constant<bool, true>
false_type std::integral_constant<bool, false>

Índice

[editar] Tipos de membro

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 T
type std::integral_constant<T,v>

[editar] Constantes de membros

Nome
Original:
Name
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Value
value
expressão constante estática de T tipo com v valor
Original:
static constant expression of type T with value v
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

[editar] Funções de membro

operator value_type
converte o objeto em value_type, retorna value
Original:
converts the object to value_type, 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)

[editar] Possível implementação

template<class T, T v>
struct integral_constant {
    static constexpr T value = v;
    typedef T value_type;
    typedef integral_constant type;
    constexpr operator value_type() const { return value; }
};

[editar] Exemplo

#include <iostream>
#include <type_traits>
 
int main() 
{
    typedef std::integral_constant<int, 2> two_t;
    typedef std::integral_constant<int, 4> four_t;
 
//  static_assert(std::is_same<two_t, four_t>::value,
//                "two_t and four_t are not equal!"); 
//  error: static assertion failed: "two_t and four_t are not a same types"
 
    static_assert(two_t::value*2 == four_t::value,
       "2*2 != 4"
    );
 
    enum class my_e {
       e1,
       e2
    };
    typedef std::integral_constant<my_e, my_e::e1> my_e_e1;
    typedef std::integral_constant<my_e, my_e::e2> my_e_e2;
 
//  static_assert(my_e_e1::value == my_e::e2,
//               "my_e_e1::value != my_e::e2");
//  error: static assertion failed: "my_e_e1::value != my_e::e2"
 
    static_assert(std::is_same<my_e_e2, my_e_e2>::value,
                  "my_e_e2 != my_e_e2");
}