std::ref, std::cref

 

C++

Idioma

Conceptos

Utilidades de la biblioteca

Strings biblioteca

Contenedores biblioteca

Algoritmos biblioteca

Los iteradores biblioteca

Numéricos biblioteca

Entrada / salida de la biblioteca

Localizaciones biblioteca

Expresiones biblioteca Regular (C++11)

Operaciones de biblioteca Atómica (C++11)

Tema Biblioteca de ayuda (C++11)

 

Utilidades de la biblioteca

Escriba apoyo (basic types, RTTI, type traits)

Gestión de memoria dinámica

Gestión de errores

Programa de servicios públicos

Funciones variadic

Fecha y hora

Objetos Function

initializer_list (C++11)

bitset

hash (C++11)

Operadores relacionales 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>=

Pares y tuplas 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)

Cambiar, hacia adelante y mover 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)

 

Objetos Function

Envoltorios de función Original: Function wrappers The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
function (C++11)
mem_fn (C++11)
bad_function_call (C++11)
Enlazar Original: Bind The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
bind (C++11)
is_bind_expression (C++11)
is_placeholder (C++11)
_1, _2, _3, ... (C++11)
Envolturas de referencia Original: Reference wrappers The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
reference_wrapper (C++11)
ref cref (C++11) (C++11)
Envoltorios Operador Original: Operator wrappers The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
plus minus negate multiplies divides modulus logical_and logical_or logical_not	equal_to not_equal_to greater less greater_equal less_equal bit_and bit_or bit_xor
Negadores Original: Negators The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
unary_negate binary_negate	not1 not2
Desaprobado aglutinantes y adaptadores Original: Deprecated binders and adaptors The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
unary_function (obsoleto)
binary_function (obsoleto)
ptr_fun (obsoleto)
pointer_to_unary_function (obsoleto)
pointer_to_binary_function (obsoleto)
mem_fun (obsoleto)
mem_fun_t mem_fun1_t const_mem_fun_t const_mem_fun1_t (obsoleto) (obsoleto) (obsoleto) (obsoleto)
mem_fun_ref (obsoleto)
mem_fun_ref_t mem_fun1_ref_t const_mem_fun_ref_t const_mem_fun1_ref_t (obsoleto) (obsoleto) (obsoleto) (obsoleto)
binder1st binder2nd (obsoleto) (obsoleto)
bind1st bind2nd (obsoleto) (obsoleto)

 

Defined in header <functional>
template< class T > std::reference_wrapper<T> ref(T& t);	(1)	(ya que C + +11)
template< class T > std::reference_wrapper<T> ref( std::reference_wrapper<T> t );	(2)	(ya que C + +11)
template< class T > std::reference_wrapper<const T> cref( const T& t );	(3)	(ya que C + +11)
template< class T > std::reference_wrapper<const T> cref( std::reference_wrapper<T> t )	(4)	(ya que C + +11)

Plantillas de función y ref cref son funciones auxiliares que generan un objeto de tipo std::reference_wrapper, con deducción argumento de plantilla para determinar el argumento de plantilla del resultado .

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.

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Parámetros

t

-

lvalue referencia al objeto que debe ser envuelto o una instancia de std::reference_wrapper Original: lvalue reference to object that needs to be wrapped or an instance of std::reference_wrapper The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

Valor de retorno

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

2) ref(t.get())

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

4) cref(t.get())

Excepciones

noexcept specification:  

noexcept

  (ya que C + +11)

Ejemplo

#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

Ver también

reference_wrapper (C++11)	CopyConstructible y CopyAssignable envoltura de referencia Original: CopyConstructible and CopyAssignable reference wrapper The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (clase de plantilla)