Traversing in Doubly Linked List

by Online Tutorials Library July 22, 2014

Traversing in doubly linked list

Traversing is the most common operation in case of each data structure. For this purpose, copy the head pointer in any of the temporary pointer ptr.

then, traverse through the list by using while loop. Keep shifting value of pointer variable ptr until we find the last node. The last node contains null in its next part.

Although, traversing means visiting each node of the list once to perform some specific operation. Here, we are printing the data associated with each node of the list.

Algorithm

Step 1: IF HEAD == NULL

&nbspWRITE “UNDERFLOW”
&nbspGOTO STEP 6
[END OF IF]

Step 2: Set PTR = HEAD
Step 3: Repeat step 4 and 5 while PTR != NULL
Step 4: Write PTR → data
Step 5: PTR = PTR → next
Step 6: Exit

C Function

  #include<stdio.h>  #include<stdlib.h>  void create(int);  int traverse();  struct node  {  int data;  struct node *next;  struct node *prev;  };  struct node *head;  void main ()  {  int choice,item;  do   {  printf(“1.Append Listn2.Traversen3.Exitn4.Enter your choice?”);  scanf(“%d”,&choice);  switch(choice)  {  case 1:  printf(“nEnter the itemn”);  scanf(“%d”,&item);  create(item);  break;   case 2:  traverse();  break;   case 3:  exit(0);  break;  default:  printf(“nPlease enter valid choicen”);  }    }while(choice != 3);  }  void create(int item)  {        struct node *ptr = (struct node *)malloc(sizeof(struct node));     if(ptr == NULL)     {         printf(“nOVERFLOWn”);     }     else     {                 if(head==NULL)     {         ptr->next = NULL;         ptr->prev=NULL;         ptr->data=item;         head=ptr;     }     else      {         ptr->data=item;printf(“nPress 0 to insert more ?n”);         ptr->prev=NULL;         ptr->next = head;         head->prev=ptr;         head=ptr;     }  printf(“nNode Insertedn”);  }       }  int traverse()  {  struct node *ptr;  if(head == NULL)  {  printf(“nEmpty Listn”);  }  else   {  ptr = head;  while(ptr != NULL)  {  printf(“%dn”,ptr->data);  ptr=ptr->next;  }  }  }   

Output

1.Append List  2.Traverse  3.Exit  4.Enter your choice?1    Enter the item  23    Node Inserted  1.Append List  2.Traverse  3.Exit  4.Enter your choice?1    Enter the item  23    Press 0 to insert more ?    Node Inserted  1.Append List  2.Traverse  3.Exit  4.Enter your choice?1    Enter the item  90    Press 0 to insert more ?    Node Inserted  1.Append List  2.Traverse  3.Exit  4.Enter your choice?2  90  23  23

Next TopicDoubly Linked List

Traversing in Doubly Linked List

Traversing in doubly linked list

Algorithm

C Function

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