Namespace
Varianti

std::pair::pair

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< 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
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rel_ops::operator!=
rel_ops::operator>
rel_ops::operator<=
rel_ops::operator>=
Coppie e tuple
Original:
Pairs and tuples
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pair
tuple(C++11)
piecewise_construct_t(C++11)
piecewise_construct(C++11)
Swap, in avanti e spostare
Original:
Swap, forward and move
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swap
forward(C++11)
move(C++11)
move_if_noexcept(C++11)
declval(C++11)
 
std::pair
Membri funzioni
Original:
Member functions
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pair::pair
pair::operator=
pair::swap
Non membri funzioni
Original:
Non-member functions
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make_pair
operator=
operator!=
operator<
operator<=
operator>
operator>=
std::swap
get(C++11)
Helper classi
Original:
Helper classes
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tuple_size(C++11)
tuple_element(C++11)
 
pair();
constexpr pair();
(1) (C fino + 11)
(dal C++11)
pair( const T1& x, const T2& y );
(2)
template< class U1, class U2 >
pair( U1&& x, U2&& y );
(3) (dal C++11)
template< class U1, class U2 >
pair( const pair<U1,U2>& p );
(4)
template< class U1, class U2 >
pair( pair<U1,U2>&& p );
(5) (dal C++11)
template< class... Args1, class... Args2 >

pair( std::piecewise_construct_t,
      std::tuple<Args1...> first_args,

      std::tuple<Args2...> second_args );
(6) (dal C++11)
pair( const pair& p ) = default;
(7)
pair( pair&& p ) = default;
(8) (dal C++11)


Costruisce una nuova coppia.
Original:
Constructs a new pair.
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1)
Costruttore di default. Valore-inizializza entrambi gli elementi della coppia, first e second.
Original:
Default constructor. Value-initializes both elements of the pair, first and second.
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2)
Inizializza first con x e second con y.
Original:
Initializes first with x and second with y.
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3)
Inizializza first con std::forward<U1>(x) e second con std::forward<U2>(y).
Original:
Initializes first with std::forward<U1>(x) and second with std::forward<U2>(y).
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4)
Inizializza first con p.first e second con p.second.
Original:
Initializes first with p.first and second with p.second.
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5)
Inizializza first con std::move<U1>(p.first) e second con std::move<U2>(p.second).
Original:
Initializes first with std::move<U1>(p.first) and second with std::move<U2>(p.second).
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6)
Contratti a termine gli elementi della first_args al costruttore di first e inoltra gli elementi della second_args al costruttore di second. Questo è l'unico costruttore non predefinito che può essere utilizzato per creare una coppia di non-copiabili non mobili tipi.
Original:
Forwards the elements of first_args to the constructor of first and forwards the elements of second_args to the constructor of second. This is the only non-default constructor that can be used to create a pair of non-copyable non-movable types.
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7)
Costruttore di copia è implicitamente generato.
Original:
Copy constructor is implicitly generated.
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8)
Costruttore Move è implicitamente generato.
Original:
Move constructor is implicitly generated.
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[modifica] Parametri

x -
valore per inizializzare il primo elemento di questa coppia
Original:
value to initialize the first element of this pair
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y -
valore per inizializzare il secondo elemento di questa coppia
Original:
value to initialize the second element of this pair
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p -
coppia di valori utilizzati per inizializzare entrambi gli elementi di questa coppia
Original:
pair of values used to initialize both elements of this pair
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first_args -
tupla di argomenti del costruttore per inizializzare il primo elemento di questa coppia
Original:
tuple of constructor arguments to initialize the first element of this pair
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second_args -
tupla di argomenti del costruttore per inizializzare il secondo elemento di questa coppia
Original:
tuple of constructor arguments to initialize the second element of this pair
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[modifica] Esempio

#include <utility>
#include <string>
#include <complex>
#include <tuple>
#include <iostream>
int main()
{
    std::pair<int, float> p1;
    std::cout << "Value-initialized: "
              << p1.first << ", " << p1.second << '\n';
 
    std::pair<int, double> p2(42, 0.123);
    std::cout << "Initialized with two values: "
              << p2.first << ", " << p2.second << '\n';
 
    std::pair<char, int> p4(p2);
    std::cout << "Implicitly converted: "
              << p4.first << ", " << p4.second << '\n';
 
    std::pair<std::complex<double>, std::string> p6(
                    std::piecewise_construct, 
                    std::forward_as_tuple(0.123, 7.7),
                    std::forward_as_tuple(10, 'a'));
    std::cout << "Piecewise constructed: "
              << p6.first << ", " << p6.second << '\n';
}

Output:

Value-initialized: 0, 0
Initialized with two values: 42, 0.123
Implicitly converted: *, 0
Piecewise constructed: (0.123,7.7), aaaaaaaaaa

[modifica] Vedi anche

crea un oggetto di tipo pair, definita dai tipi di argomenti
Original:
creates a pair object of type, defined by the argument types
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(funzione di modello) [edit]