Multi-level class inheritance with inconsistent constructors

Question

I have 3 classes that derive from one another - GameScreen is the base class to which MenuScreen is derived from. I then have a third class 'TitleScreen' which derives from 'MenuScreen'.

The flow is basically from the base class: 'GameScreen' -> 'MenuScreen' -> 'TitleScreen'

The base class 'GameScreen' has no parameters in it's constructor, like wise with 'TitleScreen', however I need a parameter for 'MenuScreen'. I currently have the header files as:

GameScreen.h

class GameScreen
{
public:
    GameScreen();
}

MenuScreen.h

class MenuScreen : public GameScreen
{
public:
    MenuScreen(std::string title);
}

TitleScreen.h

class TitleScreen : public MenuScreen
{
public:
    TitleScreen(std::string title) : MenuScreen(title);
}

What I'm having difficulty trying to understand is if this is possible in C++ (I'm following a C# sample for Game State Management which does this). Reading through class inheritance in some books I have it only covers parameters inherited from the base class, were as my sample base class has no parameters.

Yes, it works exactly as you have written - except that you should call the MenuScreen constructor in the actual implementation, not in the declaration of the constructor. — jlahd, Jul 26 '13 at 18:50

score 1 · Accepted Answer · edited May 23 '17 at 11:57

1

You are missing ; after each class declaration.
If you write TitleScreen(std::string title) : MenuScreen(title) you are defining the body of the method but the body is missing... so you should put just declaration to your TitleScreen.h :
```
class TitleScreen : public MenuScreen
{
public:
    TitleScreen(std::string title);
};
```
and then place the body of the constructor to TitleScreen.cpp:
```
#include "TitleScreen.h"

TitleScreen::TitleScreen(std::string title) : MenuScreen(title)
{
    // ..
}
```

Edit: fixed the terminology accordint to this question.

edited May 23 '17 at 11:57

Community

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answered Jul 26 '13 at 18:51

nio

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You are confusing declaration with definition terminology. And it is also worth mentioning that both can go together as in C#, or separately as in your example, possibly with pros and cons. – Jul 26 '13 at 18:56

Multi-level class inheritance with inconsistent constructors

1 Answers1