std::is_assignable, std::is_trivially_assignable, std::is_nothrow_assignable
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Definido en la cabecera <type_traits>
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template< class T, class U > struct is_assignable; |
(1) | (desde C++11) |
template< class T, class U > struct is_trivially_assignable; |
(2) | (desde C++11) |
template< class T, class U > struct is_nothrow_assignable; |
(3) | (desde C++11) |
Si el std::declval<T>() = std::declval<U>() expresión está bien formado en su contexto sin evaluar, la proporciona el miembro constante
2) value
true iguales. Para cualquier otro tipo, es value
false .Original:
If the expression std::declval<T>() = std::declval<U>() is well-formed in unevaluated context, provides the member constant
value
equal true. For any other type, value
is false.The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
lo mismo que 1), pero la evaluación de la expresión de asignación no llamar a cualquier operación que no es trivial .
3) Original:
same as 1), but evaluation of the assignment expression will not call any operation that is not trivial.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
lo mismo que 1), pero la evaluación de la expresión de asignación no llamar a cualquier operación que no se noexcept .
Original:
same as 1), but the evaluation of the assignment expression will not call any operation that is not noexcept.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
Contenido |
Inherited from std::integral_constant
Member constants
value [estático] |
true si T is assignable from U , false lo contrario Original: true if T is assignable from U , false otherwise The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (miembro público estático constante) |
Member functions
operator bool |
convierte el objeto a bool, devuelve value Original: converts the object to bool, returns value The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (función miembro público) |
Member types
Tipo
Original: Type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
Definition |
value_type
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bool
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type
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std::integral_constant<bool, value> |
[editar] Ejemplo
#include <iostream> #include <string> #include <type_traits> struct Ex1 { int n; }; int main() { std::cout << std::boolalpha << "int is assignable from double? " << std::is_assignable<int, double>::value << '\n' << "int& is nothrow assignable from double? " << std::is_nothrow_assignable<int&, double>::value << '\n' << "string is assignable from double? " << std::is_assignable<std::string, double>::value << '\n' << "Ex1& is trivially assignable from const Ex1&? " << std::is_trivially_assignable<Ex1&, const Ex1&>::value << '\n'; }
Salida:
int is assignable from double? false int& is nothrow assignable from double? true string is assignable from double? true Ex1& is trivially assignable from const Ex1&? true
[editar] Ver también
(C++11)(C++11)(C++11) |
Comprueba si un tipo tiene un operador de asignación de copia Original: checks if a type has a copy assignment operator The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (plantilla de clase) |
(C++11)(C++11)(C++11) |
Comprueba si un tipo tiene un operador de asignación movimiento Original: checks if a type has a move assignment operator The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (plantilla de clase) |