# std::bad_weak_ptr

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< cpp‎ | memory

Defined in header `<memory>` |  |
class bad_weak_ptr; |  | (since C++11)

`std::bad_weak_ptr` is the type of the object thrown as exceptions by the constructors of std::shared_ptr that take std::weak_ptr as the argument, when the std::weak_ptr refers to an already deleted object.

Inheritance diagram

### Member functions

(constructor) | constructs the bad_weak_ptr object (public member function)

## std::bad_weak_ptr ::bad_weak_ptr()

bad_weak_ptr() noexcept; |  |

Constructs a new instance of `std::bad_weak_ptr`. `what()` returns an implementation-defined null-terminated byte string.

### Parameters

(none)

## Inherited from std::exception

### Member functions

(destructor) [virtual] | destroys the exception object (virtual public member function of `std::exception`)
what [virtual] | returns an explanatory string (virtual public member function of `std::exception`)

### Example

Run this code

    #include <memory>
    #include <iostream>
    int main()
    {
        std::shared_ptr<int> p1(new int(42));
        std::weak_ptr<int> wp(p1);
        p1.reset();
        try {
            std::shared_ptr<int> p2(wp);
        } catch(const std::bad_weak_ptr& e) {
            std::cout << e.what() << '\n';
        }
    }

Output:

    std::bad_weak_ptr

### See also

shared_ptr (C++11) | smart pointer with shared object ownership semantics (class template)
weak_ptr (C++11) | weak reference to an object managed by std::shared_ptr (class template)

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