Simple classes cause an error

Question

I have 3 classes coded in c++. They are all simple, but compiler gives alot error. Each class in a cpp file and header file. What can be the possible problems? One of it is "base class undefined".

class re {
  int i;
  int j;
  string a;
  re(int,int,int);
  ~re();
}

class Pre:public re {
  int k;
  public:
    Pre(int,int,int);
   ~Pre();
}

class MPre:public Pre {
  int z;
  public:
      MPre(int);
     ~Mpre(int);
}

Class definitions should end with a semi-colon(";"). Are you using a semi-colon in your actual code? (you're not using it in your example). — mfontanini, Apr 19 '12 at 18:53
can you post the errors, I mean what you have pasted could be because there is no terminating `;` at the end of the class definitions but i's difficult to guess. — EdChum, Apr 19 '12 at 18:53
you should still post your full code and error output, we cannot guess if your pasted code does not match what you compiled with — EdChum, Apr 19 '12 at 18:55
First time I see a destructor with an argument. Are you sure about that? — Some programmer dude, Apr 19 '12 at 18:56
I wrote default constructor for Pre. All errors gone. Thank you. — ds s, Apr 19 '12 at 19:00
@dss in the future you should take note of our comments if you want your questions answered correctly and promptly it shouldn't be a guessing game on stackoverflow, still good that you resolved your problem — EdChum, Apr 19 '12 at 19:01
This should help a lot http://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list — DumbCoder, Apr 19 '12 at 19:13

score 2 · Accepted Answer · answered Apr 19 '12 at 18:53

2

Possible mistakes :

re class constructor is not public. Are you aware of this?
MPre constructor gets one input, so you have to write default constructor for Pre class.
Be careful when adding header files. For example, Pre class needs re class' header file.
Also, you don't need to write destructor unless you add pointer variables to classes

answered Apr 19 '12 at 18:53

vkx

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You need a virtual destructor in case if you will use the inheritance. – AlexTheo Apr 19 '12 at 18:56
2

You will also need a destructor if you have any allocated resources, not just memory but things like files etc. too. – Some programmer dude Apr 20 '12 at 03:47

score 0 · Answer 2 · answered Apr 19 '12 at 18:55

0

For the error undefined base class, I think you haven't #included the file in which the class re is declared in the files where other classes are.

answered Apr 19 '12 at 18:55

Tamer Shlash

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score 0 · Answer 3 · answered Apr 19 '12 at 18:58

The semicolons are missing in the classes declaration. Also for good separate all the classes in the different .h .cpp files so you will avoid to include unwanted code in case you don't need it. Also in case of inheritance make sure that your destructors are virtual otherwise it will produce a memory leaks.

Also re's constructor is not public make it public.

Simple classes cause an error

3 Answers3