std::conditional
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<metanoindex/>
<tbody> </tbody>| definiert in Header <type_traits>
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template< bool B, class T, class F > struct conditional; |
(seit C++11) | |
Bietet Mitglied typedef
type, die als T definiert wird, wenn B ist true Zeitpunkt der Kompilierung, oder als F wenn B ist false .Original:
Provides member typedef
type, which is defined as T if B is true at compile time, or as F if B 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.
Mitglied Typen
Mitglied Typ
Original: Member type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
Definition |
type
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T if B == true, F if B == false
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Mögliche Implementierung
template<bool B, class T, class F>
struct conditional { typedef T type; };
template<class T, class F>
struct conditional<false, T, F> { typedef F type; };
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Beispiel
#include <iostream>
#include <type_traits>
#include <typeinfo>
int main()
{
typedef std::conditional<true, int, double>::type Type1;
typedef std::conditional<false, int, double>::type Type2;
typedef std::conditional<sizeof(int) >= sizeof(double), int, double>::type Type3;
std::cout << typeid(Type1).name() << '\n';
std::cout << typeid(Type2).name() << '\n';
std::cout << typeid(Type3).name() << '\n';
}
Output:
i
d
d