# std::get_deleter

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< cpp‎ | memory‎ | shared ptr

Defined in header `<memory>` |  |
template< class Deleter, class T > Deleter* get_deleter( const std::shared_ptr<T>& p ) noexcept; |  | (since C++11)

Access to the p's deleter. If the shared pointer p owns a deleter of type cv-unqualified `Deleter` (e.g. if it was created with one of the constructors that take a deleter as a parameter), then returns a pointer to the deleter. Otherwise, returns a null pointer.

### Parameters

p | - | a shared pointer whose deleter needs to be accessed

### Return value

A pointer to the owned deleter or `nullptr`. The returned pointer is valid at least as long as there remains at least one shared_ptr instance that owns it.

### Notes

The returned pointer may outlive the last shared_ptr if, for example, std::weak_ptrs remain and the implementation doesn't destroy the deleter until the entire control block is destroyed.

### Example

Demonstrates that std::shared_ptr deleter is independent of the shared_ptr's type.

Run this code

    #include <iostream>
    #include <memory>

    struct Foo { int i; };
    void foo_deleter(Foo * p)
    {
        std::cout << "foo_deleter called!\n";
        delete p;
    }

    int main()
    {
        std::shared_ptr<int> aptr;

        {
            // create a shared_ptr that owns a Foo and a deleter
            auto foo_p = new Foo;
            std::shared_ptr<Foo> r(foo_p, foo_deleter);
            aptr = std::shared_ptr<int>(r, &r->i); // aliasing ctor
            // aptr is now pointing to an int, but managing the whole Foo
        } // r gets destroyed (deleter not called)

        // obtain pointer to the deleter:
        if (auto del_p = std::get_deleter<void(*)(Foo*)>(aptr))
        {
            std::cout << "shared_ptr<int> owns a deleter\n";
            if (*del_p == foo_deleter)
                std::cout << "...and it equals &foo_deleter\n";
        }
        else
            std::cout << "The deleter of shared_ptr<int> is null!\n";
    } // deleter called here

Output:

    shared_ptr<int> owns a deleter
    ...and it equals &foo_deleter
    foo_deleter called!

### See also

(constructor) | std::shared_ptr constructors (public member function)
get_deleter | returns the deleter that is used for destruction of the managed object (public member function of `std::unique_ptr<T,Deleter>`)

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