std::conditional
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| Defined in header <type_traits>
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| template< bool B, class T, class F > struct conditional; |
(C + + 11以来) | |
typeとして定義されているメンバのtypedefTを提供する場合、Btrueコンパイル時、またはFですB場合falseようです.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.
目次 |
[編集] メンバータイプ
| メンバー·タイプ
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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[編集] 可能な実装
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; }; |
[編集] 例
#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
[編集] も参照してください
| (C++11) |
コンパイル時のブールに基づいた関数のオーバーロードやテンプレートの特殊化を隠します Original: hides a function overload or template specialization based on compile-time boolean The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (クラステンプレート) |
