Good day! Little question about smart pointers. In general I have pointer to BYTE array and I want to use std::shared_ptr instead of plain pointer. Here my pointer example
shared_ptr<BYTE> pointer(new BYTE[100]);
LPBYTE *old_pointer = pointer;
Of course this is invalid example but how I can assign my smartpointer to other general pointer?
You are probably asking for
std::shared_ptr<std::array<BYTE,100>> pointer(make_shared<std::array<BYTE,100>>());
LPBYTE old_pointer = pointer.get()->data();
To have another reference you can simply have a statement like this
// increases reference count
std::shared_ptr<std::array<BYTE,100>> pointer2 = pointer;
See the detailed documentations here please: std::shared_ptr constructor and std::shared_ptr::get().
Though remember:
Accessing the smart pointer's pointee using std::shared_ptr::get() bypasses the semantics and features provided by using the std::shared_ptr. That's highly discouraged, unless you very well know what you're doing with old_pointer, and if it's still in scope.
You can access the raw pointer using get_pointer(shared_ptr<>)
BYTE* raw_pointer = get_pointer(pointer);
As others point out, grabbing the raw pointer means you now have a reference that isn't counted and have a potentially dangerous situation if not careful.
Also, if you use a shared_ptr<> to hold a pointer to a raw array, you need to call delete[] on the raw pointer rather than delete. That means you'll need a custom deleter. I realize your example is likely illustrative and not literal, but still thought it worthy to point this out.
Recent versions of boost::shared_ptr can hold a dynamically allocated array. That feature is being added to the Library Fundamentals TS (part of the standardization process).
