linked stack.cpp

链式栈

#include "linked stack.h"
#include "node.h"

Error_code Linkedstack::push(const Stack_entry & item)
{
	Error_code outcome=success;
	Node *new_top=new Node(item,top_node);
	if (new_top==NULL)
	{
		return outcome=overflow;
	}
	top_node=new_top;
	return outcome;
}
/***********************************************/
Error_code Linkedstack::pop()
{
	Error_code outcome=success;
    Node *old_top=top_node;
	if (top_node==NULL)
	{
		return outcome=underflow;
	}
	top_node=old_top->next;
	delete old_top;
	return outcome;
}
/************************************************/
bool Linkedstack::empty()const
{
	bool outcome=true;
	if (top_node!=NULL)
	{
		outcome=false;
	}
	return outcome;
}
/************************************************/
Error_code Linkedstack::top(Stack_entry & item)const
{
	Error_code outcome=success;
	if (top_node==NULL)
	{
		outcome=underflow;
	}
	else
		item=top_node->entry;
}
/************************************************/
void Linkedstack::operator=(const Linkedstack & original)
{
	Node *new_top,*new_copy,*original_node=original.top_node;
	if (original_node==NULL)
	{
		new_top=NULL;
	}
	else
	{
		new_copy=new_top=new Node(original_node->entry);
		while(original_node->next!=NULL)
		{
			original_node=original_node->next;
			new_copy->next=new Node(original_node->entry);
			new_copy=new_copy->next;
		}
	}
	while (!empty())
		pop();
	top_node=new_top;
}
/***********************************************/
Linkedstack::~Linkedstack()
{
	while(!empty())
	{
		pop();
	}
}
/***********************************************/
Linkedstack::Linkedstack(const Linkedstack & original)
{
	Node *new_copy,*original_node=original.top_node;
	if (original_node==NULL)
	{
		top_node=NULL;
	}
	else
	{
		top_node=new_copy=new Node(original_node->entry);
		while (original_node->next!=NULL)
		{
			original_node=original_node->next;
			new_copy=new_copy->next;
		}
	}
}
/***********************************************/
Linkedstack::Linkedstack()
{
	 top_node=NULL;
}
/***********************************************/