Namespace
Varianti

std::ref, std::cref

Da cppreference.com.
< cpp‎ | utility‎ | functional

 
 
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)
 
Funzione oggetti
Funzione wrapper
Original:
Function wrappers
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function(C++11)
mem_fn(C++11)
bad_function_call(C++11)
Associare
Original:
Bind
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bind(C++11)
is_bind_expression(C++11)
is_placeholder(C++11)
_1, _2, _3, ...(C++11)
Wrapper di riferimento
Original:
Reference wrappers
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reference_wrapper(C++11)
ref
cref
(C++11)
(C++11)
Operatore wrapper
Original:
Operator wrappers
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Negatori
Original:
Negators
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Sconsigliata a leganti e adattatori
Original:
Deprecated binders and adaptors
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unary_function(deprecato)
binary_function(deprecato)
ptr_fun(deprecato)
pointer_to_unary_function(deprecato)
pointer_to_binary_function(deprecato)
mem_fun(deprecato)
mem_fun_t
mem_fun1_t
const_mem_fun_t
const_mem_fun1_t
(deprecato)
(deprecato)
(deprecato)
(deprecato)
mem_fun_ref(deprecato)
mem_fun_ref_t
mem_fun1_ref_t
const_mem_fun_ref_t
const_mem_fun1_ref_t
(deprecato)
(deprecato)
(deprecato)
(deprecato)
binder1st
binder2nd
(deprecato)
(deprecato)
bind1st
bind2nd
(deprecato)
(deprecato)
 
Defined in header <functional>
template< class T >
std::reference_wrapper<T> ref(T& t);
(1) (dal C++11)
template< class T >
std::reference_wrapper<T> ref( std::reference_wrapper<T> t );
(2) (dal C++11)
template< class T >
std::reference_wrapper<const T> cref( const T& t );
(3) (dal C++11)
template< class T >
std::reference_wrapper<const T> cref( std::reference_wrapper<T> t )
(4) (dal C++11)
Modelli funzionali e ref cref sono funzioni di supporto che generano un oggetto di tipo std::reference_wrapper, utilizzando l'argomento detrazione modello per determinare l'argomento modello del risultato.
Original:
Function templates ref and cref are helper functions that generate an object of type std::reference_wrapper, using template argument deduction to determine the template argument of the result.
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Indice

[modifica] Parametri

t -
lvalue riferimento all'oggetto che deve essere confezionate o un'istanza di std::reference_wrapper
Original:
lvalue reference to object that needs to be wrapped or an instance of std::reference_wrapper
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[modifica] Valore di ritorno

1) std::reference_wrapper<T>(t)

2) ref(t.get())

3) std::reference_wrapper<const T>(t)

4) cref(t.get())

[modifica] Eccezioni fatte p

noexcept specification:  
noexcept
  (dal C++11)

[modifica] Esempio

#include <functional>
#include <iostream>
 
void f(int& n1, int& n2, const int& n3)
{
    std::cout << "In function: " << n1 << ' ' << n2 << ' ' << n3 << '\n';
    ++n1; // increments the copy of n1 stored in the function object
    ++n2; // increments the main()'s n2
    // ++n3; // compile error
}
 
int main()
{
    int n1 = 1, n2 = 2, n3 = 3;
    std::function<void()> bound_f = std::bind(f, n1, std::ref(n2), std::cref(n3));
    n1 = 10;
    n2 = 11;
    n3 = 12;
    std::cout << "Before function: " << n1 << ' ' << n2 << ' ' << n3 << '\n';
    bound_f();
    std::cout << "After function: " << n1 << ' ' << n2 << ' ' << n3 << '\n';
}

Output:

Before function: 10 11 12
In function: 1 11 12
After function: 10 12 12

[modifica] Vedi anche

CopyConstructible e CopyAssignable involucro di riferimento
Original:
CopyConstructible and CopyAssignable reference wrapper
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(classe template) [edit]