Difficulty compiling inherited template class
From: Greg (gregDOTdDOTsmith_at_gmail.com)
Date: 11/20/04
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Date: Sat, 20 Nov 2004 13:11:35 -0800
As an exercise, I am writing a stack class (stack.h) that inherits from a
templatized double ended queue class (deque.h)
When I attempt to compile it, I get the following error (MSVC++ 7.1):
f:\school_projects\cs121\deque\main.cpp(47): error C2662: 'Deque<T>::~Deque'
: cannot convert 'this' pointer from 'Deque' to 'Deque<T> &'
If anyone has any ideas, I would appreciate the help... I have googled on
this error, but all the cases I found don't seem to apply to this case
particularly well.
thx
Greg
//Stack.h
#include "Deque.h"
template<class T>
class Stack : public virtual Deque
{
public:
Stack();
~Stack();
void Push(T item);
T Pop();
T* Peek();
int GetCount();
};
template< class T >
Stack<T>::Stack() : Deque()
{
}
template< class T >
Stack<T>::~Stack()
{
}
template< class T >
void Stack<T>::Push(T item)
{
Deque::EnqueueHead(item);
}
template< class T >
T Stack<T>::Pop()
{
return Deque::DequeueHead();
}
template< class T >
T* Stack<T>::Peek()
{
return Deque::PeekHead();
}
template< class T >
int Stack<T>::GetCount()
{
return Deque::GetCount();
}
//
// Deque.h
#include "QueueNode.h"
template<class T>
class Deque
{
public:
Deque();
~Deque();
void EnqueueHead(T item);
T DequeueHead();
T* PeekHead() const;
void EnqueueTail(T item);
T DequeueTail();
T PeekTail() const;
bool IsEmpty() const;
int GetCount() const;
private:
void SetFirstNode(QueueNode<T>*);
QueueNode< T >* ptrHead;
QueueNode< T >* ptrTail;
};
template< class T >
Deque<T>::Deque()
{
ptrHead = NULL;
ptrTail = NULL;
}
template <class T>
Deque<T>::~Deque
{
while(this->!IsEmpty())
{DequeueHead();}
}
template<class T>
void Deque<T>::EnqueueHead(T item)
{
QueueNode<T>* newNode = new QueueNode<T>(item);
if(IsEmpty())
{
SetFirstNode(newNode);
}
else
{
//set newNode's tail pointer to current head node
newNode->ToTail = ptrHead;
//set deque's head pointer to newNode
ptrHead->ToHead = newNode;
//Set newNode's ToHead pointer to null (redundant)
newNode->ToHead = NULL;
//set deque's head pointer to newNode
ptrHead = newNode;
}
}
template<class T>
T Deque<T>::DequeueHead()
{
if(IsEmpty())
{
return 0;
}
else
{
//get value of head node
T value = ptrHead->value;
//Get ref to node to be dequeued
QueueNode<T>* dqNode = ptrHead;
//set head node pointer to pointer of second node
ptrHead = ptrHead->ToTail;
//delete dequeued node
delete dqNode;
//if dequeued node was last node in deque, set tail pointer to null
if(ptrHead == NULL)
{
ptrTail = NULL;
}
return value;
}
}
template<class T>
T* Deque<T>::PeekHead() const
{
if(IsEmpty())
{
return 0;
}
else
{
return ptrHead->value;
}
}
template<class T>
void Deque<T>::EnqueueTail(T item)
{
QueueNode<T>* newNode = new QueueNode<T>(item);
if(IsEmpty())
{
SetFirstNode(newNode);
}
else
{
//Set new tail node's head pointer to current Deque's tail pointer
newNode->ToHead = ptrTail;
//Set deque's tail pointer's tail pointer to newnode
ptrTail->ToTail = newNode;
//set newnode's tail pointer to null (redundant)
newNode->ToTail = NULL;
//set Deque's tail pointer to newnode
ptrTail = newNode;
}
}
template<class T>
T Deque<T>::DequeueTail()
{
if(IsEmpty())
{
return 0;
}
else
{
//get value of tail node
T value = ptrTail->value;
//get ref to tail node
QueueNode<T>* dqNode = ptrTail;
//set new tail node as second node from tail
ptrTail = ptrTail->ToHead;
//delete dequeued node
delete dqNode;
//if dequeued node was last node in data structure, set head pointer to null
if(ptrTail == NULL)
{
ptrHead = NULL;
}
return value;
}
}
template<class T>
T Deque<T>::PeekTail() const
{
if(IsEmpty())
{
return 0;
}
else
{
return ptrTail->value;
}
}
template< class T >
bool Deque<T>::IsEmpty() const
{
return (ptrHead == NULL);
}
template< class T >
int Deque<T>::GetCount() const
{
int count = 0;
QueueNode* ptrNode = ptrHead;
while(ptrNode != NULL)
{
count++;
ptrNode = ptrNode->ToTail;
}
return count;
}
template< class T >
void Deque<T>::SetFirstNode(QueueNode<T>* newNode)
{
ptrHead = newNode;
ptrTail = newNode;
}
//
// QueueNode.h
template<class T>
class QueueNode
{
public:
QueueNode(T value);
T value;
QueueNode* ToHead;
QueueNode* ToTail;
};
template <class T>
QueueNode< T >::QueueNode(T value)
{
value = value;
ToHead = NULL;
ToTail = NULL;
}
//
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