Question about strange constructors in class

Hi there!

Have a look at the following code in a class:

Code:

---

class D3DApp
{
protected:

D3DApp(HINSTANCE hInstance);
D3DApp(const D3DApp& rhs) = delete;
D3DApp& operator=(const D3DApp& rhs) = delete;
virtual ~D3DApp();

....omitted

---

The parts in bold have confused me. I see a constructor which takes a HINSTANCE and a destructor that can be over-ridden. But what are the other two lines in between those?

I really haven't got a clue! Thanks :)

They are respectively the copy constructor and assignment operator.
14.14 — Introduction to the copy constructor – Learn C++
22.3 — Move constructors and move assignment – Learn C++
21.12 — Overloading the assignment operator – Learn C++

The = delete means you're forbidding the use of these methods.
11.4 — Deleting functions – Learn C++

It's basically to prevent you from (accidentally) creating another copy of your app, using things like

Code:

---

D3DApp a, b;
a = b;  // nope!
D3DApp c(a);  // nope!

---

Brilliant! Thanks very much Salem :) I got some reading to do!

I had a good read of that stuff, and also recently came across it on the NetAcad course I'm doing. So no use of copy constructors allowed through either the typical a = b style nor the function a(b) style. Thanks again :)

Those lines are actually related to preventing the compiler from generating default copy constructor and copy assignment operator for the D3DApp class. By using = delete, you're essentially telling the compiler not to allow copying of D3DApp objects. This is often done to prevent unintended behavior or resource management issues, especially in classes that manage resources like memory or handles. So, in essence, those lines ensure that instances of D3DApp cannot be copied or assigned to another instance, helping to maintain the integrity of the class's design.

Thanks very much fbdf6, much appreciated :)