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std::tuple_size<std::pair>

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< cpp‎ | utility‎ | pair

 
 
 
std::pair
Member-Funktionen
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Member functions
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pair::pair
pair::operator=
pair::swap
Non-Member-Funktionen
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Non-member functions
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make_pair
operator=
operator!=
operator<
operator<=
operator>
operator>=
std::swap
get(C++11)
Helper-Klassen
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Helper classes
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tuple_size(C++11)
tuple_element(C++11)
 
Defined in header <utility>
template< class T1, class T2 >
struct tuple_size<std::pair<T1, T2>>;
(seit 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
[statisch]
integral constant with value 2
(public static Mitglied konstanten)

[Bearbeiten] Beispiel

#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

[Bearbeiten] Siehe auch

erhält die Größe der tuple bei der Kompilierung
Original:
obtains the size of tuple at compile time
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(class Template-Spezialisierung) [edit]
erhält die Größe eines array
Original:
obtains the size of an array
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(class Template-Spezialisierung) [edit]
ermittelt die Art der Elemente der pair
Original:
obtains the type of the elements of pair
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(class Template-Spezialisierung) [edit]