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std::addressof

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Defined in header <memory>
template< class T >
T* addressof(T& arg);
(seit C++11)

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

Inhaltsverzeichnis

[Bearbeiten] Parameter

arg - lvalue object or function

[Bearbeiten] Rückgabewert

Pointer to arg.

[Bearbeiten] Ausnahmen

noexcept specification:  
noexcept
  (seit C++11)

[Bearbeiten] Mögliche Implementierung

template< class T >
T* addressof(T& arg) {
    return (T*)&(char&)arg;
}

[Bearbeiten] Beispiel

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

[Bearbeiten] Siehe auch

the default allocator
(Klassen-Template) [edit]
liefert Informationen über Zeiger-ähnliche Typen
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provides information about pointer-like types
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(Klassen-Template) [edit]