Thread: Unhandled Exception (Vectors)

I get and Unhandled Exception error when running the following code snippit below. It works without the nested class but I wanted the inplementation to be closer to the requirement specs. Only part of the code is provided below. I would be happy to paste more if it is necessary.

I traced the error with debug, thinking it was the variable being passed, but any vector functions, like size, empty, etc.. cause it to crash so the value has nothing to do with it. Its like the vector cannot be accessed at all.

Furthermore, the program started working for one brief time and then would stop if tested again, or work half-way and then fail. I cannot see where the memory leak is?

Code:

template <class Elem, int size>
class Bag  {

template <class Elem>
	class StackClass  {  // Nested class withing Bag class
		friend class Bag <Elem, size>;
	

	private:
		vector<Elem> *sVector;
        
		const bool Push (const Elem &pushValue) const  {
			cout << "\n********Pushing************\n";
                          // Note:  ERROR OCCURS WITH ANY VECTOR FUNCTION BELOW:
			cout << endl << sVector->size() << endl;
			sVector->push_back (pushValue);
                        return true;  }
};  // ************* end of Stack class definition *********

private:
		Elem *contents;  // pointer array of type: Elem

public:
		Bag();
		~Bag();
		StackClass<Elem> *Stack;

};  // end class Bag definition


template <class Elem, int size>
Bag<Elem, size>::Bag() {        // Constructor
	
	StackClass<Elem> *Stack = new StackClass<Elem>;
	contents = new Elem [size];
	Stack->sVector = new vector<Elem>;
}

template <class Elem, int size>
const bool Bag<Elem, size>::Grab (int &item) { 
	int count;

        if (!Stack->Push (contents [count]))
	     cout << "\n***** Stack Error, Push Failed !! *****\n\n";
			}  // end push
	return true;

}  // end Grab

What's the overall goal of the project and why do you want a pointer to a vector?

vector<Elem> *sVector; //pointer to a vector???

If you are trying to make a two dimensional container I'd use a vector of vectors and avoid use of pointers/new, etc.

Code:

template <class Elem, int size>
const bool Bag<Elem, size>::Grab (int &item) { 
	int count;

        if (!Stack->Push (contents [count]))
	     cout << "\n***** Stack Error, Push Failed !! *****\n\n";
			}  // end push
	return true;

}  // end Grab

Here you are using count without initializing it unless you just didn't post the initialization code.

These crazy errors can be such a mystery. Anyway, it started working after I changed the following BAD CODE:

Code:

public:
	StackClass<Elem> *Stack;

};  // end class Bag definition


template <class Elem, int size>
Bag<Elem, size>::Bag() {        // Constructor
	
	StackClass<Elem> *Stack = new StackClass<Elem>;
}

(I guess I defined the stack pointer twice and instead of just referencing it) GOOD CODE:

Code:

public:
		StackClass<Elem> *Stack;

};  // end class Bag definition


template <class Elem, int size>
Bag<Elem, size>::Bag() {        // Constructor
	
	Stack = new StackClass<Elem>;
}