Namespace
Varianti

std::tuple_size<std::pair>

Da cppreference.com.
< cpp‎ | utility‎ | pair

 
 
Utilità libreria
Tipo di supporto (basic types, RTTI, type traits)
Gestione della memoria dinamica
La gestione degli errori
Programma di utilità
Funzioni variadic
Data e ora
Funzione oggetti
initializer_list(C++11)
bitset
hash(C++11)
Gli operatori relazionali
Original:
Relational operators
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
rel_ops::operator!=
rel_ops::operator>
rel_ops::operator<=
rel_ops::operator>=
Coppie e tuple
Original:
Pairs and tuples
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
pair
tuple(C++11)
piecewise_construct_t(C++11)
piecewise_construct(C++11)
Swap, in avanti e spostare
Original:
Swap, forward and move
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
swap
forward(C++11)
move(C++11)
move_if_noexcept(C++11)
declval(C++11)
 
std::pair
Membri funzioni
Original:
Member functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
pair::pair
pair::operator=
pair::swap
Non membri funzioni
Original:
Non-member functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
make_pair
operator=
operator!=
operator<
operator<=
operator>
operator>=
std::swap
get(C++11)
Helper classi
Original:
Helper classes
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
tuple_size(C++11)
tuple_element(C++11)
 
Defined in header <utility>
template< class T1, class T2 >
struct tuple_size<std::pair<T1, T2>>;
(dal 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
[statico]
integral constant with value 2
(pubblico membro statico costante)

[modifica] Esempio

#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

[modifica] Vedi anche

ottiene la dimensione della tuple al momento della compilazione
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.

(classe modello di specializzazione) [edit]
ottiene la dimensione di un 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.

(classe modello di specializzazione) [edit]
ottiene il tipo di elementi di 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.

(classe modello di specializzazione) [edit]