C LAB‎ > ‎(Sem2) Data Structures‎ > ‎

Qx14. WAP to implement Doubly LL.

posted Mar 13, 2011, 10:24 AM by Neil Mathew   [ updated Mar 13, 2011, 10:41 AM ]

SOURCE CODE:

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#include <stdlib.h>
 
int count;
 
struct node
{
       int info;
       struct node* next;
       struct node* prev;
}*start,*ptr;
 
int INS( int ITEM, int pos)
{
    struct node * newnode;
    newnode= (struct node*) malloc ( sizeof(struct node) );
    newnode->info=ITEM;
    newnode->next=NULL;
    newnode->prev=NULL;
    
    // ERROR HANDLING #1 - Overflow?
    if(newnode==NULL)
    {
     printf("\n No Memory Left to create a node. ");
     return 0;
    }
    
    //ERROR HANDLING #2 - Position Overlimits
    if( pos<=0 || pos>count+1 )
    {
     printf("\n Position Entered Over limits. ");
     return 0;
    }
 
    // Condition 1: Entering the first node of LL
    if(start==NULL)
    {
     start=newnode;
     count=1;
    }
    // Condition 2: Entering node to the first position
    else if(pos==1)
    {
     newnode->next=start;
     start->prev=newnode;
     start=newnode;
     count++;
    }
    // Condition 3: Enterting a node to last position
    else if(pos==count+1)
    {
     int i;
     ptr=start;
     for(i=2; i<=pos-1; i++)
     ptr=ptr->next;
     
     newnode->next=ptr->next;
     newnode->prev=ptr;
     ptr->next=newnode;
     count++;
    }
    // Condition 4: Entering a node to any other position
    else
    {
     int i;
     ptr=start;
     for(i=2; i<=pos-1; i++)
     ptr=ptr->next;
     
     newnode->next=ptr->next;
     newnode->prev=ptr;
     (ptr->next)->prev=newnode; // Note Line.
     ptr->next=newnode;
     count++;
    }
    
 return 1;
}
 
int DEL(int pos)
{
    struct node *temp;
    
    // ERROR HANDLING #1 - Underflow
    if(start==NULL)
    {
     printf("\n There are no Nodes to delete. ");
     return 0;
    }
    
    // ERROR HANDLING #2 - Position Overlimits
    if( pos<=0 || pos>count )
    {
     printf("\n Position Entered Over limits. ");
     return 0;
    }
    
    // Condition 1: Deleting Node at 1st position OR Last Node in LL.
    if(pos==1)
    {
     temp=start;
     start=start->next;
     free(temp);
     count--;
    }
    // Condition 2: Deleting node at last position
    else if(pos==count)
    {
     for(ptr=start; ptr->next!=NULL; ptr=ptr->next);
     
     (ptr->prev)->next=NULL;
     printf("\n Deleting Node with value = %d" , ptr->info);
     free(ptr);
     
     count--;
    }   
    // Condition 3; Deleting node at any other position
    else
    {
     int i;
     ptr=start;
     for(i=2; i<=pos; i++)
     ptr=ptr->next;
     
     (ptr->prev)->next=ptr->next;
     (ptr->next)->prev=ptr->prev;
     printf("\n Deleting Node with value = %d",ptr->info);
     free(ptr);
     count--;
    }
    return 1;
}
int F_Traverse()
{
    if(start==NULL)
    {
     printf("\n There are no elements in this Linked List.");
     return 0;
    }
    
    printf("\n [");
    for(ptr=start; ptr!=NULL; ptr=ptr->next)
    printf(" - %d",ptr->info);
    printf(" - ]\n");
 
    return 1;
}
 
int R_Traverse()
{
    if(start==NULL)
    {
     printf("\n There are no elements in this Linked List.");
     return 0;
    }
    
    for(ptr=start; ptr->next!=NULL; ptr=ptr->next);
    
    printf("\n [");
    for(; ptr!=NULL; ptr=ptr->prev)
    printf(" - %d",ptr->info);
    printf(" - ]\n");
 
    return 1;
}
 
int Search(int ITEM)
{
    int i;
    for(i=1,ptr=start; ptr!=NULL; ptr=ptr->next,i++)
    if(ptr->info==ITEM)
    return i;
    
    return -1;
}
 
int main()
{
    int ch,success;
    int ITEM; int pos=1;
    
    start=NULL;
    count=0;
    
    do
    {
    printf("\n ___________________________________________________ ");
    printf("\n MENU: ");
    printf("\n\n 1. Insert a Node. ");
    printf("\n 2. Delete a Node. ");
    printf("\n 3. Forward Traversing the Doubly LL. ");
    printf("\n 4. Reverse Traversing the Doubly LL. ");
    printf("\n 5. Search for a node. ");
    printf("\n 0. EXIT. ");
    printf("\n\n Your Choice: ");
    scanf("%d", &ch);
 
    switch(ch)
    {
              case 1: //INSERT
              
              printf("\n Enter the Item to Insert: ");
              scanf("%d",&ITEM);
              
              if(start!=NULL)
              {
              printf("\n Enter the position: ");
              scanf("%d", &pos);
              }
              
              success=INS(ITEM, pos);
              break;
              
              case 2: //DELETE
              
              if(start!=NULL)
              {
              printf("\n Enter the position: ");
              scanf("%d", &pos);
              }
              success=DEL(pos);
              break;
              
              case 3: //Forward Traversing
              printf("\n The Elements: ");
              success=F_Traverse();
              break;
              
              case 4: //Reverse Traversing
              printf("\n The Elements: \n");
              success=R_Traverse();
              break;
              
              case 5: //Searching
              
              printf("\n Enter the Item to Search for: ");
              scanf("%d",&ITEM);
              pos=Search(ITEM);
              
              if(pos!=-1)
              printf("\n The Item is found at %d Position",pos);
              else
              printf("\n Item not found. ");
              
              break;
              
              case 0: 
              printf("\n Exiting... ");
    
    }
    }while(ch);
    
     return 1;
}
 

OUTPUT:

 ___________________________________________________
MENU: 1. Insert a Node. 2. Delete a Node. 3. Forward Traversing the Doubly LL. 4. Reverse Traversing the Doubly LL. 5. Search for a node. 0. EXIT. Your Choice: 1 Enter the Item to Insert: 23 ___________________________________________________ MENU: 1. Insert a Node. 2. Delete a Node. 3. Forward Traversing the Doubly LL. 4. Reverse Traversing the Doubly LL. 5. Search for a node. 0. EXIT. Your Choice: 1 Enter the Item to Insert: 12 Enter the position: 1 ___________________________________________________ MENU: 1. Insert a Node. 2. Delete a Node. 3. Forward Traversing the Doubly LL. 4. Reverse Traversing the Doubly LL. 5. Search for a node. 0. EXIT. Your Choice: 1 Enter the Item to Insert: 90 Enter the position: 3 ___________________________________________________ MENU: 1. Insert a Node. 2. Delete a Node. 3. Forward Traversing the Doubly LL. 4. Reverse Traversing the Doubly LL. 5. Search for a node. 0. EXIT. Your Choice: 3 The Elements: [ - 12 - 23 - 90 - ] ___________________________________________________ MENU: 1. Insert a Node. 2. Delete a Node. 3. Forward Traversing the Doubly LL. 4. Reverse Traversing the Doubly LL. 5. Search for a node. 0. EXIT. Your Choice: 4 The Elements: [ - 90 - 23 - 12 - ] ___________________________________________________ MENU: 1. Insert a Node. 2. Delete a Node. 3. Forward Traversing the Doubly LL. 4. Reverse Traversing the Doubly LL. 5. Search for a node. 0. EXIT. Your Choice: 5 Enter the Item to Search for: 12 The Item is found at 1 Position ___________________________________________________ MENU: 1. Insert a Node. 2. Delete a Node. 3. Forward Traversing the Doubly LL. 4. Reverse Traversing the Doubly LL. 5. Search for a node. 0. EXIT. Your Choice: 2 Enter the position: 1 ___________________________________________________ MENU: 1. Insert a Node. 2. Delete a Node. 3. Forward Traversing the Doubly LL. 4. Reverse Traversing the Doubly LL. 5. Search for a node. 0. EXIT. Your Choice: 3 The Elements: [ - 23 - 90 - ] ___________________________________________________ MENU: 1. Insert a Node. 2. Delete a Node. 3. Forward Traversing the Doubly LL. 4. Reverse Traversing the Doubly LL. 5. Search for a node. 0. EXIT. Your Choice: 0
 
Exiting...


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