C++ typecast: cast a pointer from void pointer to class pointer

c++ pointers void
Naveen picture Naveen · Apr 9, 2012 · Viewed 31.7k times · Source

How to cast a pointer to void object to class object?

Answer

Mike Seymour picture Mike Seymour · Apr 9, 2012

With a static_cast. Note that you must only do this if the pointer really does point to an object of the specified type; that is, the value of the pointer to void was taken from a pointer to such an object.

thing * p = whatever(); // pointer to object
void * pv = p;          // pointer to void
thing * p2 = static_cast<thing *>(pv); // pointer to the same object

If you find yourself needing to do this, you may want to rethink your design. You're giving up type safety, making it easy to write invalid code:

something_else * q = static_cast<something_else *>(pv);
q->do_something();  // BOOM! undefined behaviour.

Related questions

How to delete void pointer?

Is there anything wrong when deleting an object like this in C++? MyCls* c = new MyCls(); void* p = (void*)c; delete (MyCls*)p;

Read More
Pointer to void in C++?

I'm reading some code in the Ogre3D implementation and I can't understand what a void * type variable means. What does a pointer to void mean in C++?

Read More
What are the differences between a pointer variable and a reference variable in C++?

I know references are syntactic sugar, so code is easier to read and write. But what are the differences?

Read More