Hey guys,
I am trying to write a method (copyStack())that copies the elements of one stack to another. So I am using a Type variable and a while loop, assigning the top of the first stack to the variable, and then using the push method to push the Type variable into my second stack (then poping the first stack). However, whenever it comes time to print the second stack (the one I am trying to copy into), nothing shows up. I know that the program is reaching the copyStack function, and I know that when I put a regular string in for the Type variable, it passes that string along. But for some reason, when I use the variable, nothing happens! Here's what I've got...
//Header File: linkedStack.h
#ifndef H_StackType
#define H_StackType
#include <iostream>
#include <cassert>
usingnamespace std;
//*************************************************************
// Author: D.S. Malik
//
// This class specifies the basic operation on a stack as a
// linked list.
//*************************************************************
//Definition of the node
template <class Type>
struct nodeType
{
Type info;
nodeType<Type> *link;
};
template <class Type>
class linkedStackType
{
public:
const linkedStackType<Type>& operator=
(const linkedStackType<Type>&);
//Overload the assignment operator.
bool isEmptyStack() const;
//Function to determine whether the stack is empty.
//Postcondition: Returns true if the stack is empty;
// otherwise returns false.
bool isFullStack() const;
//Function to determine whether the stack is full.
//Postcondition: Returns false.
void initializeStack();
//Function to initialize the stack to an empty state.
//Postcondition: The stack elements are removed;
// stackTop = NULL;
void push(const Type& newItem);
//Function to add newItem to the stack.
//Precondition: The stack exists and is not full.
//Postcondition: The stack is changed and newItem is
// added to the top of the stack.
Type top() const;
//Function to return the top element of the stack.
//Precondition: The stack exists and is not empty.
//Postcondition: If the stack is empty, the program
// terminates; otherwise, the top element of
// the stack is returned.
void pop();
//Function to remove the top element of the stack.
//Precondition: The stack exists and is not empty.
//Postcondition: The stack is changed and the top
// element is removed from the stack.
linkedStackType();
//Default constructor
//Postcondition: stackTop = NULL;
linkedStackType(const linkedStackType<Type>& otherStack);
//Copy constructor
~linkedStackType();
//Destructor
//Postcondition: All the elements of the stack are removed.
private:
nodeType<Type> *stackTop; //pointer to the stack
void copyStack(const linkedStackType<Type>& otherStack);
//Function to make a copy of otherStack.
//Postcondition: A copy of otherStack is created and
// assigned to this stack.
};
//Default constructor
template <class Type>
linkedStackType<Type>::linkedStackType()
{
stackTop = NULL;
}
template <class Type>
bool linkedStackType<Type>::isEmptyStack() const
{
return(stackTop == NULL);
} //end isEmptyStack
template <class Type>
bool linkedStackType<Type>:: isFullStack() const
{
returnfalse;
} //end isFullStack
template <class Type>
void linkedStackType<Type>:: initializeStack()
{
nodeType<Type> *temp; //pointer to delete the node
while (stackTop != NULL) //while there are elements in
//the stack
{
temp = stackTop; //set temp to point to the
//current node
stackTop = stackTop->link; //advance stackTop to the
//next node
delete temp; //deallocate memory occupied by temp
}
} //end initializeStack
template <class Type>
void linkedStackType<Type>::push(const Type& newElement)
{
nodeType<Type> *newNode; //pointer to create the new node
newNode = new nodeType<Type>; //create the node
newNode->info = newElement; //store newElement in the node
newNode->link = stackTop; //insert newNode before stackTop
stackTop = newNode; //set stackTop to point to the
//top node
} //end push
template <class Type>
Type linkedStackType<Type>::top() const
{
assert(stackTop != NULL); //if stack is empty,
//terminate the program
return stackTop->info; //return the top element
}//end top
template <class Type>
void linkedStackType<Type>::pop()
{
nodeType<Type> *temp; //pointer to deallocate memory
if (stackTop != NULL)
{
temp = stackTop; //set temp to point to the top node
stackTop = stackTop->link; //advance stackTop to the
//next node
delete temp; //delete the top node
}
else
cout << "Cannot remove from an empty stack." << endl;
}//end pop
template <class Type>
void linkedStackType<Type>::copyStack
(const linkedStackType<Type>& otherStack)
{
nodeType<Type> *newNode, *current, *last;
if (stackTop != NULL) //if stack is nonempty, make it empty
initializeStack();
if (otherStack.stackTop == NULL)
stackTop = NULL;
else
{
current = otherStack.stackTop; //set current to point
//to the stack to be copied
//copy the stackTop element of the stack
stackTop = new nodeType<Type>; //create the node
stackTop->info = current->info; //copy the info
stackTop->link = NULL; //set the link field of the
//node to NULL
last = stackTop; //set last to point to the node
current = current->link; //set current to point to
//the next node
//copy the remaining stack
while (current != NULL)
{
newNode = new nodeType<Type>;
newNode->info = current->info;
newNode->link = NULL;
last->link = newNode;
last = newNode;
current = current->link;
}//end while
}//end else
} //end copyStack
//copy constructor
template <class Type>
linkedStackType<Type>::linkedStackType(
const linkedStackType<Type>& otherStack)
{
stackTop = NULL;
copyStack(otherStack);
}//end copy constructor
//destructor
template <class Type>
linkedStackType<Type>::~linkedStackType()
{
initializeStack();
}//end destructor
//overloading the assignment operator
template <class Type>
const linkedStackType<Type>& linkedStackType<Type>::operator=
(const linkedStackType<Type>& otherStack)
{
if (this != &otherStack) //avoid self-copy
copyStack(otherStack);
return *this;
}//end operator=
#endif
