Espaces de noms
Variantes
    Actions

      std::conditional

      De cppreference.com
      < cpp‎ | types
       
      C++
       
      Bibliothèque d'utilitaires
       
      Soutien aux types fondamentaux
      Les types de base
      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.
      Types fondamentaux
      Fixe les types entiers largeur (C++11)
      Limites numériques
      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 numérique limite interface
      Informations sur le type d'exécution
      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.
      Caractères de type
      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.
      Catégories de type primaire
      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_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
      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)
      Opérations prises en charge
      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)
      Les relations et les requêtes de propriété
      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)
      Modifications de type
      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.
      Transformations de type
      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)
      Tapez constantes traits
      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)
       
      Déclaré dans l'en-tête <type_traits>
      template< bool B, class T, class F >
      struct conditional;
      		(depuis C++11)

      Fournit un élément typedef type, qui est défini comme T si B est true lors de la compilation, ou comme F si B est false .

      Sommaire

      [modifier] Types de membres

      Type du membreDéfinition
      typeT si B == true, sinon F

      [modifier] Mise en œuvre possible

      template<bool B, class T, class F>
struct conditional { typedef T type; };
 
template<class T, class F>
struct conditional<false, T, F> { typedef F type; };

      [modifier] Exemple

      #include <iostream>
#include <type_traits>
#include <typeinfo>
 
int main() 
{
    typedef std::conditional<true, int, double>::type Type1;
    typedef std::conditional<false, int, double>::type Type2;
    typedef std::conditional<sizeof(int) >= sizeof(double), int, double>::type Type3;
 
    std::cout << typeid(Type1).name() << '\n';
    std::cout << typeid(Type2).name() << '\n';
    std::cout << typeid(Type3).name() << '\n';
}

      Résultat :

      i
d
d

      [modifier] Voir aussi

      (C++11)
      cache une surcharge de fonction ou de spécialisation modèle basé sur la compilation booléen
      Original:
      hides a function overload or template specialization based on compile-time boolean
      The text has been machine-translated via Google Translate.
      You can help to correct and verify the translation. Click here for instructions.

      (classe générique) [edit]
      Récupérée de « https://fr.cppreference.com/mwiki/index.php?title=cpp/types/conditional&oldid=49998 »