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std::is_polymorphic

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Type traits
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is_const(C++11)
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integral_constant(C++11)
 
Defined in header <type_traits>
template< class T >
struct is_polymorphic;
(seit C++11)
Wenn T eine polymorphe Klasse (das heißt, eine Klasse, oder erklärt, erbt mindestens eine virtuelle Funktion) ist, stellt das Mitglied konstanten value gleich true. Für jede andere Art, value ist false .
Original:
If T is a polymorphic class (that is, a class that declares or inherits at least one virtual function), provides the member constant value equal true. For any other type, value is false.
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Inhaltsverzeichnis

Inherited from std::integral_constant

Member constants

value
[statisch]
true wenn T is a polymorphic class type , false anders
Original:
true if T is a polymorphic class type , false otherwise
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(public static Mitglied konstanten)

Member functions

operator bool
wandelt das Objekt bool, gibt value
Original:
converts the object to bool, returns value
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(öffentliche Elementfunktion)

Member types

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

[Bearbeiten] Notes

Nur polymorphe Klassen enthalten versteckt RTTI Informationen, die es möglich zu untersuchen, und wandeln sie mit dynamic_cast macht .
Original:
Only polymorphic classes contain hidden RTTI information which makes it possible to examine and convert them with dynamic_cast.
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[Bearbeiten] Beispiel

#include <iostream>
#include <type_traits>
 
struct A {
    int m;
};
 
struct B {
    virtual void foo();
};
 
struct C : B {};
 
int main()
{
    std::cout << std::boolalpha;
    std::cout << std::is_polymorphic<A>::value << '\n';
    std::cout << std::is_polymorphic<B>::value << '\n';
    std::cout << std::is_polymorphic<C>::value << '\n';
}

Output:

false
true
true

[Bearbeiten] Siehe auch

(C++11)
checks if a type is a class type (but not union type)
(Klassen-Template) [edit]
prüft, ob ein Typ ist abstrakt Klassentyp
Original:
checks if a type is abstract class type
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(Klassen-Template) [edit]