I am creating the shared_ptr in a function and returning raw pointer from that function. To get the underlying raw pointer from the shared_ptr I am using .get()

If i am using the raw pointer in a function and assigning to the function of type raw pointer it is working without any issue. But if i create the shared_ptr and while returning, it is calling the destructor and deleting the memory assigned to the object and crashing.

How to assign the shared_ptr object to the function of type raw pointer?

CMyClass::CMyClass()
{
}

CMyClass::~CMyClass()
{
}

CMyClass* CreateClassInstance()
{
std::shared_ptr<CMyClass> l_MyClassInterface = std::make_shared<CMyClass>();
return l_MyClassInterface.get();
}

CMyClass* CreateClassInstance()
{
CMyClass* l_MyClassInterface = new CMyClass();
return l_MyClassInterface;
}

auto l_pMyClassInterface = CreateClassInstance();

CodePudding user response：

Yes, what @user17732522 said.

In the code as written, l_MyClassInterface is going out of scope when your first version of CreateClassInstance returns, taking your newly created object with it. When you return a shared_ptr, as opposed to the pointer returned by get(), the mechanism that it uses to keep track of the reference count for your object kicks in and stops that from happening. (Well, in principle. In practise, copy elision usually / always ensures that the shared_ptr created by make_shared is returned directly to the caller, but that's a detail.)

The other (inferior) solution would be to return the pointer returned by new directly and assign it to a shared_ptr in the caller. But that is error-prone, and not recommended.