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cref Function

Constructs a const reference_wrapper from an argument.

template<class Ty>
    reference_wrapper<const Ty> cref(const Ty& arg);
template<class Ty>
    reference_wrapper<const Ty> cref(const reference_wrapper<Ty>& arg);

Ty

The type of the argument to wrap.

arg

The argument to wrap.

The first function returns reference_wrapper<const Ty>(arg.get()). You use it to wrap a const reference. The second function returns reference_wrapper<const Ty>(arg). You use it to rewrap a wrapped reference as a const reference.

 

// std_tr1__functional__cref.cpp 
// compile with: /EHsc 
#include <functional> 
#include <iostream> 
 
int neg(int val) 
    { 
    return (-val); 
    } 
 
int main() 
    { 
    int i = 1; 
 
    std::cout << "i = " << i << std::endl; 
    std::cout << "cref(i) = " << std::cref(i) << std::endl; 
    std::cout << "cref(neg)(i) = " 
        << std::cref(&neg)(i) << std::endl; 
 
    return (0); 
    } 
 
i = 1
cref(i) = 1
cref(neg)(i) = -1

Header: <functional>

Namespace: std

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