Thread: Derived classes and initialization lists

Hi, I have a base class something like:

Code:

class MyClass
{
   protected:
      const int nRecords;
      int *records;
   
   public:
      ...
};

And I would like my derived classes to initialize the 'const int nRecords' value in their constructor, i.e.

Code:

class MyDerivedClass : public MyClass
{
   public:
      MyDerivedClass() : nRecords(10) {}

   ...
}

When I try to compile such code however, I get the follwing error (using DevC++ v4.x):

"Class 'MyDerivedClass' does not have any field named 'nRecords'"

Any suggestions as to how I could work around this?

dt

>Any suggestions as to how I could work around this?
Don't try to, it's a good thing. Your classes should generally not share members except through a well defined interface:

Code:

#include <iostream>

class A {
  int i;
public:
  A(int init)
    : i(init)
  {}
protected:
  int get()
  {
    return i;
  }
};

class B: public A {
  int j;
public:
  B()
    : A(10), j(20)
  {}

  void print()
  {
    std::cout<< get() <<" -- "<< j <<std::endl;
  }
};

int main()
{
  B b;

  b.print();
}

Ah, I see. So I can call the base class' constructor in the derived class' init list and pass that a value to initialise my constant?

Nice one, thanks.