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    std::is_union

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    <metanoindex/>

     
    C++
     
    Bibliothèque d'utilitaires
     
    Soutien aux types fondamentaux
    Les types de base
    Original:
    Basic types
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    Types fondamentaux
    Fixe les types entiers largeur (C++11)
    Limites numériques
    Original:
    Numeric limits
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    numeric_limits
    C numérique limite interface
    Informations sur le type d'exécution
    Original:
    Runtime type information
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    Caractères de type
    Original:
    Type traits
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    Catégories de type primaire
    Original:
    Primary type categories
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    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)
    Les propriétés du type
    Original:
    Type properties
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    is_const (C++11)
    is_volatile (C++11)
    is_pod (C++11)
    is_empty (C++11)
    is_polymorphic (C++11)
    is_abstract (C++11)
    Opérations prises en charge
    Original:
    Supported operations
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    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)
    Les relations et les requêtes de propriété
    Original:
    Relationships and property queries
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    is_same (C++11)
    is_base_of (C++11)
    is_convertible (C++11)
    alignment_of (C++11)
    rank (C++11)
    extent (C++11)
    Modifications de type
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    Type modifications
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    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)
    Transformations de type
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    Type transformations
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    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)
    Tapez constantes traits
    Original:
    Type trait constants
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    integral_constant (C++11)
     
    <tbody> </tbody>
    Déclaré dans l'en-tête <type_traits>
    template< class T > struct is_union;
    		 (depuis C++11)
    Si T est un type d'union, fournit du membre de constante value true égale. Pour tout autre type, value est false .
    Original:
    If T is a union type, provides the member constant value equal true. For any other type, value is false.
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    Inherited from std::integral_constant

    Member constants

    value
    [
    statique
    Original:
    static
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    ]
    true si T is a union type , false autrement
    Original:
    true if T is a union type , false otherwise
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    (constante membre statique publique)

    Member functions

    operator bool
    convertit l'objet en bool, retourne value
    Original:
    converts the object to bool, returns value
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    (fonction membre publique)

    Member types

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

    Exemple

    #include <iostream>
#include <type_traits>

struct A {};

typedef union {
    int a;
    float b;
} B;

struct C {
    B d;
};

int main() 
{
    std::cout << std::boolalpha;
    std::cout << std::is_union<A>::value << '\n';
    std::cout << std::is_union<B>::value << '\n';
    std::cout << std::is_union<C>::value << '\n';
    std::cout << std::is_union<int>::value << '\n';
}

    Résultat : 

    false
true
false
false

    Voir aussi

    (C++11)
    		 checks if a type is a class type (but not union type)
    (classe générique) [edit]