C++ inherit class shows no default constructor

Question

I'm creating a few classes and I decided to create a basic class that other classes will just inherit that basic class

So here is my basic class header

#pragma once

#include "ImageService.h"

class State
{
public:
    State( ImageService& is );
    ~State();

    void Update();

};

don't worry about the methods, they aren't the problem. So now I go ahead and create a IntroState like so (header file)

#pragma once

#include "State.h"

class IntroState : public State
{
public:
    IntroState(ImageService& imageService);
    ~IntroState();

    GameState objectState;
};

and here is the cpp file

#include "IntroState.h"


IntroState::IntroState(ImageService& imageService)
{
    //error here
}


IntroState::~IntroState()
{
}

at the constructor it is stating "no default constructor for class "State"", now what I think is going on is, the default constructor for State needs a imageService reference passed to it. So how would I pass the imageservice in this constructor to the state constructor?

+1 for nice formatting and actually, almost answering the question himself. — gsamaras, May 22 '14 at 20:50

score 8 · Accepted Answer · answered May 22 '14 at 20:30

8

Your base class has no default constructor, which is what gets implicitly called in your current derived class constructor. You need to explicitly call the base's constructor:

IntroState::IntroState(ImageService& imageService) : State(imageService)
{

}

answered May 22 '14 at 20:30

juanchopanza

223,364
34
402
480

I literally just typed that and it worked :D, Cheers for the quick reply though – Canvas May 22 '14 at 20:30

score 3 · Answer 2 · answered May 22 '14 at 20:30

3

The usual way:

IntroState::IntroState(ImageService& imageService)
    : State(imageService)
{
}

answered May 22 '14 at 20:30

Luchian Grigore

253,575
64
457
625

I literally just typed that and it worked :D, Cheers for the quick reply though – Canvas May 22 '14 at 20:30

score 1 · Answer 3 · edited May 23 '17 at 10:32

You should call the constructor of State too, like this:

IntroState::IntroState(ImageService& imageService)
    : State(imageService) {
}

Tip: Don't use:

#pragma once, use guards!

Example:

#ifndef GRANDFATHER_H
#define GRANDFATHER_H

class A {
    int member;
};

#endif /* GRANDFATHER_H */

You can read more about the include guards in wikipedia.

You see #pragma is not standard. Neither became in C++11 (link).

C++ inherit class shows no default constructor

3 Answers3