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std::has_virtual_destructor

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< cpp‎ | types

 
 
Utilità libreria
Tipo di supporto (basic types, RTTI, type traits)
Gestione della memoria dinamica
La gestione degli errori
Programma di utilità
Funzioni variadic
Data e ora
Funzione oggetti
initializer_list(C++11)
bitset
hash(C++11)
Gli operatori relazionali
Original:
Relational operators
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rel_ops::operator!=
rel_ops::operator>
rel_ops::operator<=
rel_ops::operator>=
Coppie e tuple
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Pairs and tuples
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pair
tuple(C++11)
piecewise_construct_t(C++11)
piecewise_construct(C++11)
Swap, in avanti e spostare
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Swap, forward and move
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swap
forward(C++11)
move(C++11)
move_if_noexcept(C++11)
declval(C++11)
 
Tipo di supporto
Tipi base
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Basic types
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Tipi fondamentali
Larghezza fissa interi tipi (C++11)
Limiti numerici
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Numeric limits
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numeric_limits
C numerico limita interfaccia
Informazioni sul tipo di runtime
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Runtime type information
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Tipo tratti
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Type traits
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Categorie di tipo primario
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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)
Proprietà del tipo
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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)
Operazioni supportate
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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)
I rapporti e le query di proprietà
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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)
Tipo modifiche
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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)
Tipo di trasformazioni
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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)
Digitare costanti tratto
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Type trait constants
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integral_constant(C++11)
 
Defined in header <type_traits>
template< class T >
struct has_virtual_destructor;
(dal C++11)
Se T è un tipo con un distruttore virtuale, fornisce l'elemento costante value true uguali. Per qualsiasi altro tipo, è value false.
Original:
If T is a type with a virtual destructor, provides the member constant value equal true. For any other type, value is false.
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Indice

Inherited from std::integral_constant

Member constants

value
[statico]
true se T has a virtual destructor , false altrimenti
Original:
true if T has a virtual destructor , false otherwise
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(pubblico membro statico costante)

Member functions

operator bool
converte l'oggetto in bool, restituisce value
Original:
converts the object to bool, returns value
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(membro pubblico funzione)

Member types

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

[modifica] Note

Se una classe ha un distruttore pubblico virtuale, può essere derivato da, e l'oggetto derivato può essere eliminato senza problemi tramite un puntatore all'oggetto di base (C++FAQ Lite 20.7)
Original:
If a class has a public virtual destructor, it can be derived from, and the derived object can be safely deleted through a pointer to the base object (C++FAQ Lite 20.7)
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[modifica] Esempio

#include <iostream>
#include <type_traits>
#include <string>
#include <stdexcept>
 
int main()
{
    std::cout << std::boolalpha
              << "std::string has a virtual destructor? "
              << std::has_virtual_destructor<std::string>::value << '\n'
              << "std::runtime_error has a virtual destructor? "
              << std::has_virtual_destructor<std::runtime_error>::value << '\n';
}

Output:

std::string has a virtual destructor? false
std::runtime_error has a virtual destructor? true

[modifica] Vedi anche

Verifica se un tipo ha un distruttore non cancellato
Original:
checks if a type has a non-deleted destructor
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(classe template) [edit]