std::tuple_size<std::pair>
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| Definido no cabeçalho <utility>
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| template< class T1, class T2 > struct tuple_size<std::pair<T1, T2>>; |
(desde C++11) | |
The partial specialization of std::tuple_size for pairs provides a compile-time way to obtain the number of elements in a pair, which is always 2, using tuple-like syntax.
Members | |
| value [estática] |
integral constant with value 2 (membro estático público constante) |
[editar] Exemplo
#include <iostream> #include <utility> #include <tuple> template<class T> void test(T t) { int a[std::tuple_size<T>::value]; // can be used at compile time std::cout << std::tuple_size<T>::value << '\n'; // or at run time } int main() { test(std::make_tuple(1, 2, 3.14)); test(std::make_pair(1, 3.14)); }
Saída:
3 2
[editar] Veja também
| obtém o tamanho de tuple em tempo de compilação Original: obtains the size of tuple at compile time The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (especialização modelo. classe) | |
| obtém o tamanho de um array Original: obtains the size of an array The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (especialização modelo. classe) | |
| obtém o tipo dos elementos de pair Original: obtains the type of the elements of pair The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (especialização modelo. classe) | |