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std::addressof

From cppreference.com
 
 
 
 
Defined in header <memory>
template< class T >
T* addressof(T& arg);
(since C++11)

Obtains the actual address of the object or function arg, even in presence of overloaded operator&

Contents

[edit] Parameters

arg - lvalue object or function

[edit] Return value

Pointer to arg.

[edit] Exceptions

noexcept specification:  
noexcept
  (since C++11)

[edit] Possible implementation

[edit] Example

operator& may be overloaded for a pointer wrapper class to obtain a pointer to pointer:

#include <iostream>
#include <memory>
 
template<class T>
struct Ptr {
   T* data;
   Ptr(T* arg) : data(arg) {}
   ~Ptr() {delete data;}
   T** operator&() { return &data; }
};
 
template<class T>
void f(Ptr<T>* p) {
    std::cout << "Ptr overload called with p = " << p << '\n';
}
 
void f(int** p) {
    std::cout << "int** overload called with p = " << p << '\n';
}
 
int main()
{
    Ptr<int> p(new int(42));
    f(&p);                 // calls int** overload
    f(std::addressof(p));  // calls Ptr<int>* overload
}

Output:

int** overload called with p = 0012FF64
Ptr overload called with p = 0012FF64

[edit] See also

the default allocator
(class template) [edit]
provides information about pointer-like types
(class template) [edit]