C++ Program to Implement Sorted Doubly Linked List

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This C++ program displays the nodes of a doubly linked list in which linked list can be traversed from the last node to first node or vice versa.

Here is the source code of the C++ program to display the values present in the nodes from head to the tail and in reverse. This C++ program is successfully compiled and run on DevCpp, a C++ compiler. The program output is given below.

  1. /*
  2.  * C++ Program to Implement Sorted Doubly Linked List
  3.  */
  4. #include<stdio.h>
  5. #include<conio.h>
  6. #include<iostream>
  7. using namespace std;
  8. int c = 0;
  9. struct node
  10. {
  11.     node *next, *prev;
  12.     int data;
  13. }*head = NULL, *tail = NULL, *p = NULL, *r = NULL, *np = NULL;
  14. void create(int x)
  15. {
  16.     np = new node;
  17.     np->data = x;
  18.     np->next = NULL;
  19.     np->prev = NULL;
  20.     if (c == 0)
  21.     {
  22.         tail = np;
  23.         head = np;
  24.         p = head;
  25.         p->next = NULL;
  26.         p->prev = NULL;
  27.         c++;
  28.     }
  29.     else
  30.     {
  31.         p = head;
  32.         r = p;
  33.     if (np->data < p->data)
  34.     {
  35.         np->next = p;
  36.         p->prev = np;
  37.         np->prev = NULL;
  38.         head = np;
  39.         p = head;
  40.         do
  41.         {
  42.             p = p->next;
  43.         }
  44.         while (p->next != NULL);
  45.         tail = p;
  46.     }
  47.     else if (np->data > p->data)
  48.     {
  49.         while (p != NULL && np->data > p->data)
  50.         {
  51.             r = p;
  52.             p = p->next;
  53.         if (p == NULL)
  54.         {
  55.             r->next = np;
  56.             np->prev = r;
  57.             np->next = NULL;
  58.             tail = np;
  59.             break;
  60.         }
  61.         else if (np->data < p->data)
  62.         { 
  63.             r->next = np;
  64.             np->prev = r;
  65.             np->next = p;
  66.             p->prev = np;
  67.             if (p->next != NULL)
  68.             {
  69.                 do
  70.                 {
  71.                     p = p->next;
  72.                 }
  73.                 while (p->next !=NULL);
  74.             }
  75.             tail = p;
  76.             break;
  77.          }
  78.        }
  79.      }
  80.    }
  81. }
  82. void traverse_tail()
  83. {
  84.     node *t = tail;
  85.     while (t != NULL)
  86.     {
  87.         cout<<t->data<<"\t";
  88.         t = t->prev;
  89.     }
  90.     cout<<endl;
  91. }
  92. void traverse_head()
  93. {
  94.     node *t = head;
  95.     while (t != NULL)
  96.     {
  97.         cout<<t->data<<"\t";
  98.         t = t->next;
  99.     }
  100.     cout<<endl;
  101. }
  102. int main()
  103. {
  104.     int i = 0, n, x, ch;
  105.     cout<<"enter the no of nodes\n";
  106.     cin>>n;
  107.     while (i < n)
  108.     {
  109.         cout<<"\nenter value of node\n";
  110.         cin>>x;
  111.         create(x);
  112.         i++;
  113.     }
  114.     cout<<"\nTraversing Doubly Linked List head first\n";
  115.     traverse_head();
  116.     cout<<"\nTraversing Doubly Linked List tail first\n";
  117.     traverse_tail();
  118.     getch();
  119. }

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Output
 
enter the no of nodes
7
 
enter value of node
4
 
enter value of node
2
 
enter value of node
8
 
enter value of node
1
 
enter value of node
9
 
enter value of node
6
 
enter value of node
3
 
Traversing Doubly Linked List head first
1       2       3       4       6       8       9
 
Traversing Doubly Linked List tail first
9       8       6       4       3       2       1

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn