**fig3_6.txt**

/* 1*/	template <class Etype>
/* 2*/	class List
/* 3*/	{
/* 4*/	  protected:
/* 5*/	    // The list is a linked list with a header node.

/* 6*/	    struct Node
/* 7*/	    {
/* 8*/	        Etype Element;
/* 9*/	        Node *Next;

/*10*/	        // Constructor for node.
/*11*/	        Node( Etype E = 0, Node *N = NULL ) :
/*12*/	            Element( E ), Next( N ) { }
/*13*/	    };

/*14*/	    Node *List_Head;
/*15*/	    Node *Current_Pos;

/*16*/	    void Destroy_List( );	// An incorrect routine in Fig. 3.15.
/*17*/	    void Delete_List( );	// The  correct routine in Fig. 3.16.

/*18*/	    List( List & Value );   // Disable call by value.

/*19*/	  public:
/*20*/	    // Constructor.
/*21*/	    List( ) : List_Head ( new Node ), Current_Pos( List_Head ) { }
/*22*/	 
/*23*/	    // Destructor.
/*24*/	    virtual ~List( ) { Delete_List( ); }

/*25*/	    // Operators.
/*26*/	    const List & operator = ( List & Value );
/*27*/	    const List & operator ++ ( );
/*28*/	    int operator ! ( ) const;
/*29*/	    Etype operator ( ) ( ) const;

/*30*/	    // Member functions.
/*31*/	    int Is_Empty( ) const { return List_Head->Next == NULL; }
/*32*/	    virtual int Find( const Etype & X );
/*33*/	    virtual int Find_Previous( const Etype & X );
/*34*/	    int In_List( const Etype & X );
/*35*/	    void First( ) { if( List_Head->Next != NULL )
/*36*/	                            Current_Pos = List_Head->Next; }
/*37*/	    void Header( ) { Current_Pos = List_Head; }
/*38*/	    int Remove( const Etype & X );
/*39*/	    virtual void Insert( const Etype & X );
/*40*/	    virtual void Insert_As_First_Element( const Etype & X );
/*41*/	};