std::tuple_size<std::pair>
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| Defined in header <utility>
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| template< class T1, class T2 > struct tuple_size<std::pair<T1, T2>>; |
（C++11 起） | |
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 [静态的] </ SPAN></div></div>
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integral constant with value 2 （公共静态成员常量） |
[编辑] 为例
#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)); }
Output:
3 2
[编辑] 另请参阅
| 在编译时获得的大小 tuple 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. （类模板专业化） | |
| 获得的 array大小 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. （类模板专业化） | |
pair的元素获得的类型 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. （类模板专业化） | |
