std::is_assignable, std::is_trivially_assignable, std::is_nothrow_assignable
Aus cppreference.com
![]() |
This page has been machine-translated from the English version of the wiki using Google Translate.
The translation may contain errors and awkward wording. Hover over text to see the original version. You can help to fix errors and improve the translation. For instructions click here. |
definiert in Header <type_traits>
|
||
template< class T, class U > struct is_assignable; |
(1) | (seit C++11) |
template< class T, class U > struct is_trivially_assignable; |
(2) | (seit C++11) |
template< class T, class U > struct is_nothrow_assignable; |
(3) | (seit C++11) |
Wenn der Ausdruck std::declval<T>() = std::declval<U>() in unevaluierten Rahmen wohlgeformt, bietet das Mitglied konstanten
2) value
gleich true. Für jede andere Art, value
ist 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.
wie 1), aber eine Evaluierung der Abtretung Ausdruck wird nicht nennen sämtliche Aufgaben, die nicht trivial ist .
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.
wie 1), aber die Auswertung der Abtretung Ausdruck wird nicht nennen jede Operation, die nicht noexcept wird .
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.
Inhaltsverzeichnis |
Inherited from std::integral_constant
Member constants
value [statisch] |
true wenn T is assignable from U , false anders 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. (public static Mitglied konstanten) |
Member functions
operator bool |
wandelt das Objekt bool, gibt 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. (öffentliche Elementfunktion) |
Member types
Type
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
|
bool
|
type
|
std::integral_constant<bool, value> |
[Bearbeiten] Beispiel
#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'; }
Output:
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
[Bearbeiten] Siehe auch
(C++11) (C++11) (C++11) |
prüft, ob ein Typ hat eine Kopie Zuweisungsoperator 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. (Klassen-Template) |
(C++11) (C++11) (C++11) |
prüft, ob ein Typ hat einen Umzug Zuweisungsoperator 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. (Klassen-Template) |