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/ Power Programmierung / Power-Programmierung (Tewi)(1994).iso / magazine / dbms_mag / 9107 / embay_c / llist.cpp < prev    next >
C/C++ Source or Header  |  1991-03-13  |  1KB  |  63 lines
  1. // == llist.cpp === member functions for LinkedList class ===========
  2. //                  Wes Peterson
  3.  
  4. #include "llist.h"
  5.  
  6. LinkedList::~LinkedList(void)   // destructor
  7. {
  8.     ll_node *this_node = first_node;
  9.  
  10.     while(this_node != NULL)    {
  11.         first_node = this_node->next_node;
  12.         delete this_node;
  13.         this_node = first_node;
  14.         }
  15. } 
  16.  
  17. void LinkedList::add_node(ll_node *new_node)
  18. {
  19.     if(curr_node == NULL)    {
  20.         new_node->prev_node = NULL;
  21.         if(first_node != NULL)    {
  22.             new_node->next_node = first_node;
  23.             first_node->prev_node = new_node;
  24.             }
  25.         else    {
  26.             new_node->next_node = NULL;
  27.             last_node = new_node;
  28.             }
  29.         first_node = new_node;
  30.         }
  31.     else    {
  32.         new_node->next_node = curr_node->next_node;
  33.         new_node->prev_node = curr_node;
  34.         if(curr_node == last_node)
  35.             last_node = new_node;
  36.         else
  37.             curr_node->next_node->prev_node = new_node;
  38.         curr_node->next_node = new_node;
  39.     }
  40.     curr_node = new_node;
  41. }
  42.  
  43. ll_node *LinkedList::get_next_node(void)
  44. {
  45.     if(curr_node == NULL)
  46.         curr_node = first_node;
  47.     else
  48.         curr_node = curr_node->next_node;
  49.  
  50.     return(curr_node);
  51. }
  52.  
  53. ll_node *LinkedList::get_prev_node(void)
  54. {
  55.     if(curr_node == NULL)
  56.         curr_node = last_node;
  57.     else
  58.         curr_node = curr_node->prev_node;
  59.  
  60.     return(curr_node);
  61. }
  62.  
  63.