El std::to_address , introducido en C++20, se usa para obtener la dirección representada por el puntero especificado sin formar una referencia al apuntado. El std::addressof existente no puede hacer std::addressof(*ptr) porque *ptr no siempre es un objeto. El std::to_address nos resuelve estos problemas.
Sintaxis:
template class Ptr constexpr auto to_address(const Ptr& p) noexcept; template class T constexpr T* to_address(T* p) noexcept;
Parámetros: este método acepta un parámetro p que es el puntero elegante o sin procesar cuya dirección se debe encontrar.
Valor devuelto: Este método devuelve el puntero Raw que representa la dirección del puntero p.
Los siguientes ejemplos demuestran el uso de std::address
Ejemplo 1 :
// C++ code to show
// the use of std::address
#include <iostream>
#include <memory>
using namespace std;
// Allocate memory and return
// the pointer to that memory
template <class A>
auto allocator_new(A& a)
{
auto p = a.allocate(1);
try {
allocator_traits<A>::construct(
a, to_address(p));
}
catch (...) {
a.deallocate(p, 1);
throw;
}
cout << "Pointer to Memory allocated: "
<< p << endl;
return p;
}
// Delete memory using
// pointer to that memory
template <class A>
void allocator_delete(
A& a,
typename allocator_traits<A>::pointer p)
{
allocator_traits<A>::destroy(
a, to_address(p));
a.deallocate(p, 1);
cout << "Pointer to Memory deleted: "
<< p << endl;
}
// Driver code
int main()
{
allocator<int> a;
auto p = allocator_new(a);
allocator_delete(a, p);
}
Producción:
Pointer to Memory allocated: 0x1512c20 Pointer to Memory deleted: 0x1512c20
Ejemplo 2:
// C++ code to show
// the use of std::address
#include <iostream>
#include <memory>
using namespace std;
int main()
{
// Make a unique pointer and
// use to_address to get its address
// from heap memory
cout << "Using unique pointers\n\n";
auto ptr = make_unique<int>(15);
cout << "Address of pointer to 15: "
<< to_address(ptr) << "\n";
auto ptr1 = make_unique<int>(17);
cout << "Address of pointer to 17: "
<< to_address(ptr1) << "\n";
// Use to_address to get the
// address of a dumb pointer
// from stack memory
cout << "\nUsing dumb pointers\n\n";
int i = 17;
cout << "Address of pointer to 17: "
<< to_address(&i) << "\n";
int j = 18;
cout << "Address of pointer to 18: "
<< to_address(&j) << "\n";
return 0;
}
Producción:
Using unique pointers Address of pointer to 15: 0x181ec30 Address of pointer to 17: 0x181ec50 Using dumb pointers Address of pointer to 17: 0x7fff6b454398 Address of pointer to 18: 0x7fff6b45439c
Referencia: https://en.cppreference.com/w/cpp/memory/to_address