how to cast void* to shared_ptr

Question

I have a problem with an OpenGL project, converting from a `void*` pointer to a `shared_ptr`. I am using Bullet to set pointers on the rigid body with: ``` root_physics->rigidBody->setUserPointer(&this->root_directory->handle); ``` The handle is of type `shared_ptr`. The `void*` pointer is returned by Bullet's library function, `getUserPointer()`: ``` RayCallback.m_collisionObject->getUserPointer() ``` To convert back to `mytype`, `static_cast` is not working: ``` std::shared_ptr u_poi = static_cast< std::shared_ptr >( RayCallback.m_collisionObject->getUserPointer() ); ``` The error, at compilation time: ``` /usr/include/c++/4.8/bits/shared_ptr_base.h:739:39: error: invalid conversion from ‘void*’ to ‘mytype*’ [-fpermissive] ``` Any idea how I can convert from the `void*` returned by `getUserPointer()` to `shared_ptr`?

Accepted Answer

Since you are storing a pointer to an instance of `std::shared_ptr` you need to cast the value returned by `getUserPointer` to `std::shared_ptr<>*` instead of just `std::shared_ptr<>`. ``` std::shared_ptr* u_poi = static_cast< std::shared_ptr* >(RayCallback.m_collisionObject->getUserPointer()); ```

how to cast void* to shared_ptr<mytype>

Solution

Problem