Virtual Functions and pointers

Spogliani · #1 07-11-2008, 05:21 AM

Hi to everyone

I'm writing this post because I have some problems accessing a function of a class through a pointer.

This is the situation:
I have a pointer to a class. The class inherits two virtual functions from an abstract base class.

The problem is the following:
When I try to call the function from the pointer I receive the following error at run-time: "Unhandled exception at 0x004251d8 in MyApplication.exe: 0xC0000005: Access violation reading location 0x00000000."

Can somebody help me, please?

here the declaration of the pointer and the functions:

Code:

//baseclass.h
class MyBaseClass
{
public:
  virtual void Start() = 0;
  virtual void Stop() = 0;
};
//class.h
class MyClass : public MyBaseClass
{
public:
  MyClass();
  void Stop();
};
//pointer
static MyClass *MyClassptr;
 
//myclass.cpp
MyClass::MyClass()
{
  MyClassptr=this;
}
//main.cpp
int main()
{
    MyClass MyNewClass;
    MyClassptr->Start();
    return 0;
}

ranjittechie · #2 07-15-2008, 01:58 AM

Hi,
First of all you have to define the Start() and Stop() functions.Otherwise it will take MyClass as abstract class.

After Definining these fucntions i run this same code it works fine

so try it again it works
For further queries kindly revert back