<1> The specification of Iterafor class

    template  <Class Item>
    class Bag_Iterator()  {
         public :
              Bag_Iterator() ;
              vold attach (const Bag <Item>& ) ;
              vold adcance() ;
              Item current() const ;
              bool is_item() const ;

<2> Usage

    Bag <Int>  foo ;
    Bag_Iterator <Int>  iterator ;
    - - - - - - - - -
    for ( iterafor.attach(foo) ; iterator.is_item() ; iterafor.advance() )
          cout << iterafor.current() << endl ;
also the following works
    Bag_Iterafor <Int>  itr1  itr2 ;
    for ( itr1.attach(foo) ; itr1.is_item() ; itr(advance() )
          for (itr2.attach(foo) ; itr2.is_item() ; itr2.advance() ) {
                    - - - -
          }

1. Stack :

   	a data structer of order entries such 
   	that entries can only be insented anol removed
   	at one end (called top)

   
   
2. LIFO :

   	last-in / first out

   
   
3. The Stack ADT -- specification and documentation
   

   
   specification (see p309)
   
     template class :
   
     stacks of integers float
   
     capcity
   
     capcity of stack (fixed-size first)
   			
     member function
    
         push      :  push an item to stack
         pop       :  pop on item from stack
         peek      :  peek the top item
         size      :  obtain the total no of items
         is.empty  :  examine if stack is empty
   
     Stack errors 
   
         stack underflow  : pop from on empty stack
         stack overfloew  : push into a full stack
   
    documentation  (page 309)

4. example reversing a word

              apple -> elppa