c++ Inheritance class constructor

Question

I have a slight problem where to be honest I am totally confused with derived class constructors and need some help.

I have a base class with the parameterised constructor:

Element::Element(RandomNumber &rnd, Console &console) 
: rnd(rnd), console(console)

and the derived class constructor of

Jetsam::Jetsam(RandomNumber rnd, Console console):Element(rnd,console)

Basically I want to pass the parameters that are used within the base class constructor into the derived class constructor. I have tried a number of different ways and at the moment I am getting the error message 'no initializer for'.

Does anyone have any help for me or could assist me in understanding my problem. Any help would be much appreciated.

Thank you for your time,

Alyn.

edit :

IntelliSense: "Jetsam::Jetsam(RandomNumber rnd, Console console)" provides no         initializer for:  e:\c++\my game\my game\jetsam.cpp   7

edit:

Element::Element(RandomNumber &rnd, Console &console) 
: rnd(rnd), console(console)
{

}

Jetsam::Jetsam(RandomNumber rnd, Console console):Element(rnd,console)
{

}

Can you post the full error? You've given only 3 words from the error. — Joseph Mansfield, Apr 08 '13 at 11:53
Are your member variables declared as references? If so, your derived ctor also needs the same signature as the base. — Roger Rowland, Apr 08 '13 at 11:56
@RogerRowland Yes they are declared as references, so how would I use the same sigs? — Alyn, Apr 08 '13 at 12:07
Can you post a minimal code sample that reproduces the problem? — juanchopanza, Apr 08 '13 at 12:18
What is true: "Yes they are declared as references" or "they are type of class RandomNumber and Console" ? — borisbn, Apr 08 '13 at 12:37
Please provide a minimal class definition of both classes and their member variables, i.e. provide an [SSCCE](http://sscce.org/) — Arne Mertz, Apr 08 '13 at 12:53

score 0 · Answer 1 · answered Apr 08 '13 at 11:55

0

Jetsam::Jetsam(RandomNumber rnd, Console console): Element::Element(rnd,console);

The above code sample should work.

answered Apr 08 '13 at 11:55

Games Brainiac

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Roger Rowland · Answer 2 · 2013-04-08T12:42:24.690

0

Ref my comment - if your member variables are declared as references, you will need to define your derived constructor like this:

Jetsam::Jetsam(RandomNumber &rnd, Console &console):Element(rnd,console)

For example, the following code compiles ok for me:

// dummy classes for use as member variables
class RandomNumber{};
class Console{};

// base class
class Element
{
public:
    Element(RandomNumber &rnd, Console &console) : rnd(rnd), console(console) {}

    // member variables
    RandomNumber& rnd;
    Console& console;
};

// derived class
class Jetsam : public Element
{
public:
    Jetsam(RandomNumber &rnd, Console &console) : Element(rnd, console) {}
};

I've assumed that your declaration is similar to the above. Can you edit your question if it's significantly different?

edited Apr 08 '13 at 12:42

answered Apr 08 '13 at 12:09

Roger Rowland

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This is what I initially used and still had the say error as above – Alyn Apr 08 '13 at 12:15
Is there anything else you would like to see, my derived class constructors contains nothing within its body at the moment – Alyn Apr 08 '13 at 12:33
Can you show a cut-down copy of your two classes that is similar in size to my code example above and that doesn't compile? – Roger Rowland Apr 08 '13 at 12:37
I've edited it slightly, but I unsure as to what else you would like. – Alyn Apr 08 '13 at 12:46
If you chang `Jetsam::Jetsam(RandomNumber rnd, Console console):Element(rnd,console)` to `Jetsam::Jetsam(RandomNumber &rnd, Console &console):Element(rnd,console)` it matches my example, which is ok. What error do you get if you do that? – Roger Rowland Apr 08 '13 at 12:49
I've done that and get the exact same error as mentioned in the first edit that I mentioned, the solutions that I have been given have not solved this error. – Alyn Apr 08 '13 at 12:55

c++ Inheritance class constructor

2 Answers2