//
// CS 202 program 10_linklist2.cpp
// Written by D.C. Williams for 10/28/03 class
//
// Implementation of a doubly linked list; doubly linked lists
// have two pointers, one pointing forward and one pointing backwards.
//
// This version does not require a leading blank record.
//


#include <iostream.h>
#include <stdio.h>
#include <string.h>

const int MAXCHAR = 20;   // for limiting the size of the strings 

                                                 
struct Record       
{                     
   char number[MAXCHAR];  // each word has an assigned number
   char word[MAXCHAR];    // the word itself  
   Record *pnext;         // pointer to next record
   Record *pprev;         // pointer (to previous record
};

void Forward_show_list(Record *);   
void Reverse_show_list(Record *);  
void Delete(Record *, char del);

int main()  
{
   char choice;
   char del[MAXCHAR];
 
           
   Record *pnew = 0;                                                                                                                            
   Record *pfirst = 0;           
   Record *plast = 0;             
   Record *pcurrent = 0;         
   Record *pactive = 0;         
   Record *pprev_t = 0;   // temporary pointers
   Record *pnext_t = 0;   // temporary pointers
       
   cout << "\n\nProgram to manipulate words using a doubly linked list";
      
   do
   {      
      cout << "\n\n-----------------------------------------------";   
      cout << "\n(c)reate new record    (q)uit"              ; 
      cout << "\n(d)elete record"                            ;       
      cout << "\n(f)orward view list    (r)everse view list" ;  
   
       
      cout << "\n\nPlease select: ";
      cin >> choice; 
      cin.ignore();          

      if (choice == 'q')
         exit(0);              
   
      else if (choice == 'c')
      {
         pnew = new Record;     // store address of newly-created record in pnew
         
         if (pfirst == 0)       // if this is the first record, 
         {
            pfirst = pnew;      // then set these
            pcurrent = pnew; 
            pnew->pprev = 0;
         }          
              
         cout  << "\n\nEnter data for new record: " << endl;
   
         cout << "\nWord number: ";
         cin.getline(pnew->number,MAXCHAR,'\n'); 
     
         cout << "\nWord: ";
         cin.getline(pnew->word,MAXCHAR,'\n');
          
         pnew->pnext = 0;             // zero the forward pointer in new record          
          
         if (pcurrent != pnew)        // set pointers if not the first record
         {
            pcurrent->pnext = pnew;
            pnew->pprev = pcurrent;     
          }         
                
         pcurrent = pnew;            // set pcurrent to filled-in pnew
         
         plast = pcurrent;           // set plast to new end of list    
      }   
         
      else if (choice == 'f')
         Forward_show_list(pfirst);  // show the whole list, forward direction
         
      else if (choice == 'r')
         Reverse_show_list(plast);  // show the whole list, reverse direction 
         
      else if (choice == 'd')
         {
	 cout << "\n\n\nSelect a record to delete:" << endl;
	  Forward_show_list(pfirst);
	  cout << "\n\n\n\nDelete Word Number -->";
	  cin >> del;
	  
          Delete(pfirst, del);
	 } 
	  
	  
                                                                                           
      else
         cout << endl << "Invalid choice!"<< endl;
     
   } while (1);   

   return 0;
}  

              
void Delete(Record *pfirst, char del)
 {

 cout << "\n\npfirst word --==> " << pfirst->word;
 
 if (pfirst->number = del )
 
cout << endl << del;

   return;
 }