Stack Implementation Using Single Linked List

/*
Author:B.Vinod Kumar
email: vinod_cse2008@yahoo.com

  This is a program for implementation of the stack using single linked list.
  The operations performed on a stack are

  1)push(): This is the function which is for insertion(pushing)of an element into stack
              
      It is similar to the insertion of an element at the end of a single linked list
     
            see  the function insert_end() in the program for operations of single linked list

  2)pop(): This is the function which is for deletion(popping up) of an element from the stack

           It is similar to the deletion of an element at the end of a single linked list

     see  the function delete_end() in the program for operations of single linked list

  3)stack_display():This is the function which is for displaying the elements of a stack

    
      It is similar to the forward traversal of a single linked list

      see  the function ftraverse() in the program for operations of single linked list

note:
Stack is a list of elements in which insertions and deletions are at the same end of the list called top.
The other end is known as Bottom.Insertion is also known as push,deletion is also known as pop

*/
#include<iostream.h>
#include<stdlib.h>
class stack
{
 int element;
 stack* next;
public:
 stack* push(stack*,int);
 stack* pop(stack*);
 void stack_display(stack*);
}*head,object;
stack* stack::push(stack* head,int key)
{
 stack* temp,*temp1;
 temp1=head;
 temp=new stack;
 temp->element=key;
 temp->next=NULL;
 if(head==NULL)
  head=temp;
 else
 {
 while(head->next!=NULL)
  head=head->next;
 head->next=temp;
 head=temp1;
 }
 return head;
}
stack* stack::pop(stack* head)
{
 stack* temp;
 if(head!=NULL)
 {
 temp=head;
 if(head->next==NULL)
 {
  cout<<"\nthe pooped element from the stack is: "<<head->element<<endl;
  return NULL;
 }
 while(head->next->next!=NULL)
 head=head->next;
 cout<<"the popped element from the stack is  "<<head->next->element;
 cout<<endl;
 head->next=head->next->next;
 head=temp;
 return head;
 }
 else
 {
  cout<<"\nit is impossible to pop an element from the stack as ";
  return head;
 }
}
void stack::stack_display(stack* head)
{
 if(head!=NULL)
 {
 while(head->next!=NULL)
 {
  cout<<head->element<<"->";
  head=head->next;
 }
 cout<<head->element;
 cout<<endl;
 }
 else
  cout<<"the stack is empty\n";
}  
void choice()
{
  int key,ch;
 cout<<"\nchoose the operation to be performed\n";
 cout<<"\n1.push\t2.pop\t3.exit\n\n";
 cin>>ch;
head=NULL;
while(1)
{
 switch(ch)
 {
 case 1:
  
 cout<<"——————————————————————————–\n";
  cout<<"\nenter the element to be pushed\n";
  cin>>key;
  head=object.push(head,key);
  cout<<"\nthe stack after push operation is \n";
  object.stack_display(head);
  
 cout<<"——————————————————————————–\n";
  break;

 case 2:
 cout<<"\n“““““““““““““““““““““““““““““““““““““““\n";
  head=object.pop(head);
  cout<<"\nthe stack after pop operation is :\n";
  object.stack_display(head);
  
 cout<<"\n“““““““““““““““““““““““““““““““““““““““\n";
  break;
 case 3:
  exit(1);
 default:
  cout<<"\nenter the correct choice\n";
  break;
 }
cout<<"\nchoose the operation to be performed\n";
 cout<<"\n1.push\t2.pop\t3.exit\n";
 cin>>ch;
}
}
void main()
{
choice();
}