Namespace
Varianti

std::tie

Da cppreference.com.
< cpp‎ | utility‎ | tuple

 
 
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::tuple
Membri funzioni
Original:
Member functions
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tuple::tuple
tuple::operator=
tuple::swap
Non membri funzioni
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 classi
Original:
Helper classes
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tuple_size
tuple_element
uses_allocator
ignore
 
Defined in header <tuple>
template< class... Types >
tuple<Types&...> tie( Types&... args );
(dal C++11)
Crea una tupla di riferimenti lvalue alle sue argomentazioni o istanze di std::ignore.
Original:
Creates a tuple of lvalue references to its arguments or instances of std::ignore.
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Indice

[modifica] Parametri

args -
zero o più argomenti lvalue per costruire la tupla da
Original:
zero or more lvalue arguments to construct the tuple from
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[modifica] Valore di ritorno

Un oggetto che contiene std::tuple referenes lvalue.
Original:
A std::tuple object containing lvalue referenes.
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[modifica] Eccezioni

noexcept specification:  
noexcept
  (dal C++11)

[modifica] Esempio

std::tie può essere utilizzato per introdurre confronto lessicografico di una struttura o di estrarre una tupla:
Original:
std::tie can be used to introduce lexicographical comparison to a struct or to unpack a tuple:
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#include <iostream>
#include <string>
#include <set>
#include <tuple>
 
struct S {
    int n;
    std::string s;
    float d;
    bool operator<(const S& rhs) const
    {
        // compares n to rhs.n,
        // then s to rhs.s,
        // then d to rhs.d
        return std::tie(n, s, d) < std::tie(rhs.n, rhs.s, rhs.d);
    }
};
 
int main()
{
    std::set<S> set_of_s; // S is LessThanComparable
 
    S value{42, "Test", 3.14};
    std::set<S>::iterator iter;
    bool inserted;
    // unpacks the return value of insert into iter and inserted
    std::tie(iter, inserted) = set_of_s.insert(value);
    if(inserted)
        std::cout << "Value was inserted sucessfully\n";
}

Output:

Value was inserted sucessfully
crea un oggetto tuple del tipo definito dai tipi di argomenti
Original:
creates a tuple object of the type defined by the argument types
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(funzione di modello) [edit]
crea un tuple di riferimenti rvalue
Original:
creates a tuple of rvalue references
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(funzione di modello) [edit]
crea un tuple concatenando un numero qualsiasi di tuple
Original:
creates a tuple by concatenating any number of tuples
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(funzione di modello) [edit]
segnaposto per saltare un elemento quando si scompatta un tuple utilizzando tie
Original:
placeholder to skip an element when unpacking a tuple using tie
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(costante) [edit]