Espacios de nombres
Variantes
Acciones

std::integral_constant

De cppreference.com
< cpp‎ | types

 
 
Utilidades de la biblioteca
Escriba apoyo (basic types, RTTI, type traits)
Gestión de memoria dinámica
Gestión de errores
Programa de servicios públicos
Funciones variadic
Fecha y hora
Objetos Function
(C++11)
Operadores relacionales
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.
Pares y 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.
(C++11)
Cambiar, hacia adelante y mover
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.
(C++11)
(C++11)
(C++11)
 
Escriba apoyo
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 fundamentales
Tipos fijos ancho enteros (C++11)
Límites 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.
C numérico limita interfaz
Información de tipo en tiempo de ejecución
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.
Caracteres 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.
Categorías primarias 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.
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Propiedades 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.
(C++11)
(C++11)
(C++11)
Operaciones compatibles
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.
Relaciones y consultas de propiedad
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.
(C++11)
(C++11)
(C++11)
(C++11)
Modificaciones de tipo
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.
(C++11)(C++11)(C++11)
Transformaciones de 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.
(C++11)
(C++11)
(C++11)
Escriba constantes rasgos
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 en la cabecera <type_traits>
template< class T, T v >
struct integral_constant;
(desde C++11)
std::integral_constant envuelve una constante estática del tipo especificado. Es la clase base para las C + + .. rasgos 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.
Dos especializaciones para el bool tipo están disponibles:
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>

Contenido

[editar] Tipos de miembros

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 miembros

Nombre
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
expresión estática constante de T tipo con 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] Las funciones miembro

operator value_type
convierte el objeto a value_type, devuelve 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.

(función miembro público)

[editar] Posible implementación

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] Ejemplo

#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");
}