C++ knowledge

Tell me what is the basic difference between a virtual base class and an abstract base class.

Never heard of it :(

A virtual class is a class with a virtual function. An abstract class is a class that has a pure virtual function. One cannot create abstract classes (only subclasses of abstract classes). However, non-abstract virtual classes can be instantiated. Confusing enough? :).

Code:

---

class virtualClass {
public:
    virtual void someVirtualFunc();
};

class abstractClass {
public:
    virtual void pureVirtualFunc()=0;
};

---

Yea, that IS confusing...

>> Yea, that IS confusing...

Well, not really. Its actually quite logical.

eg.

Code:

---

class Teacher
{
public:
    virtual void Teacher();

    char fname[256];
    char sname[256];
   
    virtual void TeachClass();
}

---

In the above class we have an abstract class called teacher. It has its contructor and a pure virtual function called 'TeachClass()'. Obviously this function would be differernt according to each different type of teacher (eg. Science teacher). The science teacher would be a subclass of Teacher and it would overload the pure virtual functions with their own version of them like the following.

Code:

---

class ScienceTeacher : public Teacher
{
    void TeachClass()
    {
        // do special science stuff
    }
}

---

Its not that confusing after all :D

You're wrong... it's SO Confusing!! :(

Don't fret... it'll just take some time to 'click' with you I guess... It makes sense though! :p

In face_master's example, TeachClass() is virtual function member of Teacher, which means that when you derive a class from Teacher (excuse the terminology :)) TeachClass() can be redefined to fit that class if it chooses not to use the default from Teacher if it's defined

I just read what I posted and I think I probably confused you more :(

Look at some tutorials...

One other thing... you cannot create instances of abstract classes; remember this.

Code:

---

abstractClass ac;

---

Cannot be done

>Confusing enough? :).
Only to those who do not already understand it. This seems to be the case with almost everything in C++. ;)

-Prelude