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std::tuple_size<std::tuple>

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< cpp‎ | utility‎ | tuple

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C++
 
Utilities-Bibliothek
 
std::tuple
Member-Funktionen
Original:
Member functions
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tuple::tuple
tuple::operator=
tuple::swap
Non-Member-Funktionen
Original:
Non-member functions
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make_tuple
tie
forward_as_tuple
None
operator=
operator!=
operator<
operator<=
operator>
operator>=
std::swap
get
Helper-Klassen
Original:
Helper classes
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tuple_size
tuple_element
uses_allocator
ignore
 
definiert in Header <tuple>
template< class T >
class tuple_size; /*undefined*/
 (1) (seit C++11)
template< class... Types >

class tuple_size<tuple<Types...> >

 : public std::integral_constant<std::size_t, sizeof...(Types)> { };
 (2) (seit C++11)
template< class T >

class tuple_size<const T>
 : public std::integral_constant<
             typename std::remove_cv<decltype(std::tuple_size<T>::value)>::type,

             std::tuple_size<Tp>::value> { };
 (3) (seit C++11)
template< class T >

class tuple_size< volatile T >
 : public std::integral_constant<
             typename std::remove_cv<decltype(std::tuple_size<T>::value)>::type,

             std::tuple_size<Tp>::value> { };
 (4) (seit C++11)
template< class T >

class tuple_size< const volatile T >
 : public std::integral_constant<
             typename std::remove_cv<decltype(std::tuple_size<T>::value)>::type,

             std::tuple_size<Tp>::value> { };
 (5) (seit C++11)
Bietet Zugriff auf die Anzahl der Elemente in einem Tupel als Compile-Zeit konstanter Ausdruck .
Original:
Provides access to the number of elements in a tuple as a compile-time constant expression.
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Inhaltsverzeichnis

Inherited from std::integral_constant

Member constants

value
[statisch]
 sizeof...(Types)
(public static Mitglied konstanten)

Member functions

operator std::size_t
wandelt das Objekt std::size_t, gibt value
Original:
converts the object to std::size_t, returns value
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(öffentliche Elementfunktion)

Member types

Type
Original:
Type
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 Definition
value_type std::size_t
type std::integral_constant<std::size_t, value>

[Bearbeiten] Beispiel

#include <iostream>
#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));
}

Output: 

3

[Bearbeiten] Siehe auch
erhält die Größe eines array
Original:
obtains the size of an array
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(class Template-Spezialisierung) [edit]
(C++11)
erhält die Größe eines pair
Original:
obtains the size of a pair
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(class Template-Spezialisierung) [edit]
Zugriff auf das angegebene Element des Tupels
Original:
tuple accesses specified element
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(Funktions-Template) [edit]
erhält den Typ des angegebenen Elements
Original:
obtains the type of the specified element
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(class Template-Spezialisierung) [edit]
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