std::reference_wrapper::operator()

 

C++

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Technical Specifications

 

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initializer_list (C++11)

bitset

hash (C++11)

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rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=

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pair

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Function objects

Function wrappers
function (C++11)
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bad_function_call (C++11)
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Bind
bind (C++11)
is_bind_expression (C++11)
is_placeholder (C++11)
_1, _2, _3, ... (C++11)
Reference wrappers
reference_wrapper (C++11)
refcref (C++11)(C++11)
Operator wrappers
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 bit_not (C++14)
Negators
unary_negate binary_negate	not1 not2
Deprecated binders and adaptors
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binary_function (until C++17)
ptr_fun (until C++17)
pointer_to_unary_function (until C++17)
pointer_to_binary_function (until C++17)
mem_fun (until C++17)
mem_fun_tmem_fun1_tconst_mem_fun_tconst_mem_fun1_t (until C++17)(until C++17)(until C++17)(until C++17)
mem_fun_ref (until C++17)
mem_fun_ref_tmem_fun1_ref_tconst_mem_fun_ref_tconst_mem_fun1_ref_t (until C++17)(until C++17)(until C++17)(until C++17)
binder1stbinder2nd (until C++17)(until C++17)
bind1stbind2nd (until C++17)(until C++17)

 

std::reference_wrapper

Member functions

reference_wrapper::reference_wrapper

reference_wrapper::operator=

reference_wrapper::getreference_wrapper::operator T&

reference_wrapper::operator()

 

template< class... ArgTypes > typename std::result_of<T&(ArgTypes&&...)>::type     operator() ( ArgTypes&&... args ) const;		(since C++11)

Calls the Callable object, reference to which is stored. This function is available only if the stored reference points to a Callable object.

Parameters

args

-

arguments to pass to the called function

Return value

The return value of the called function.

Exceptions

(none)

Example

Run this code

#include <iostream>
#include <functional>
 
void f1()
{
    std::cout << "reference to function called\n";
}
void f2(int n)
{
    std::cout << "bind expression called with " << n << " as the argument\n";
}
 
int main()
{
    std::reference_wrapper<void()> ref1 = std::ref(f1);
    ref1();
 
    auto b = std::bind(f2, std::placeholders::_1);
    auto ref2 = std::ref(b);
    ref2(7);
 
    auto c = []{std::cout << "lambda function called\n"; };
    auto ref3 = std::ref(c);
    ref3();
}

Output:

reference to function called
bind expression called with 7 as the argument
lambda function called

See also

getoperator T&

accesses the stored reference (public member function)