/**
* Removes the last node from the stack and returns it's data
*/
public String Pop()
{
// Check the stack isn't empty
if (IsEmpty())
throw new InvalidOperationException();
// Store the popped data
String poppedData = tail.Data;
// Remove the popped node from the stack
if (head == tail)
{
// The popped node was the only in the stack
head = null;
tail = null;
}
else
{
// The popped data was not the only in the list
StringNode nodeWalker = head;
while (nodeWalker != null)
{
if (nodeWalker.Next == tail)
{
nodeWalker.Next = null;
tail = nodeWalker;
}
nodeWalker = nodeWalker.Next;
}
}
return poppedData;
}
public int Count()
{
int count = 0;
StringNode nodeWalker = top;
while (nodeWalker != null)
{
count++;
nodeWalker = nodeWalker.Next;
}
return(count);
}
public void Push(string newString)
{
StringNode newNode = new StringNode(newString);
if (top == null)
{
top = newNode;
}
else
{
newNode.Next = top;
top = newNode;
}
}
public String Pop()
{
try
{
//get the string from the last added node on stack
String returnString = top.nodeString;
//remove the top node from the stack
top = top.Next;
return(returnString);
}
//if nothing on the stack
catch (NullReferenceException)
{
throw new NullReferenceException("no items in stack");
}
}
// Constructor
public Stack()
{
head = null;
tail = null;
}
/**
* Adds a new node the the stack
*/
public void Push(String newNodeData)
{
if (IsEmpty())
{
// If stack is empty
StringNode newNode = new StringNode(newNodeData);
head = newNode;
tail = newNode;
}
else
{
// If stack has already got at least one node
tail.Next = new StringNode(newNodeData);
tail = tail.Next;
}
}
// Constructor
public StringNode(String data)
{
this.data = data;
next = null;
}
