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std::is_convertible

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C++
 
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rel_ops::operator!=
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is_same(C++11)
is_base_of(C++11)
is_convertible(C++11)
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integral_constant(C++11)
 
Defined in header <type_traits>
template< class From, class To >
struct is_convertible;
 (a partir do C++ 11)
Se um tipo de rvalue imaginário From pode usado na instrução de retorno de uma função To retorno, isto é, se ele pode ser convertido para To usando implicit conversion, fornece o membro constante igual a value true. Caso contrário value é false.
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If an imaginary rvalue of type From can used in the return statement of a function returning To, that is, if it can be converted to To using implicit conversion, provides the member constant value equal to true. Otherwise value is false.
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Índice

Inherited from std::integral_constant

Member constants

value
[estática]
true se From is convertible to To , false contrário
Original:
true if From is convertible to To , false otherwise
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(membro estático público constante)

Member functions

operator bool
converte o objeto em bool, retorna value
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converts the object to bool, returns value
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(função pública membro)

Member types

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

[editar] Notas

Dá bem definidas resultados para tipos de referência, tipos de vazios, tipos de matriz, e tipos de função.
Original:
Gives well-defined results for reference types, void types, array types, and function types.
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[editar] Exemplo

#include <iostream>
#include <type_traits>
 
int main() 
{
    class A {};
    class B: public A {};
    class C {};
 
    bool b2a = std::is_convertible<B*, A*>::value;
    bool a2b = std::is_convertible<A*, B*>::value;
    bool b2c = std::is_convertible<B*, C*>::value;
 
    std::cout << std::boolalpha;
    std::cout << b2a << '\n';
    std::cout << a2b << '\n';
    std::cout << b2c << '\n';
}

Output: 

true
false
false
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