doubly_linkedlist.c

#include<stdio.h>  
#include<stdlib.h>
struct node  
{  
    struct node *prev;  
    struct node *next;  
    int data;  
};  
struct node *head;  
void insertion_beginning();  
void insertion_last();  
void insertion_specified();  
void deletion_beginning();  
void deletion_last();  
void deletion_specified();  
void display();  
void search();  
void main ()  
{  
int choice =0;  
    while(choice != 9)  
    {  
        printf("\n*********Main Menu*********\n");  
        printf("\nChoose one option from the following list ...\n");  
        printf("\n===============================================\n");  
        printf("\n 1.Insert in begining\n2.Insert at last \n 3.Insert at any random location \n 4.Delete from Beginning \n5.Delete from last \n 6. Delete the node after the given data \n 7.Search \n 8.Show \n 9.Exit \n ");  
        printf("\nEnter your choice?\n");  
        scanf("\n%d",&choice);  
        switch(choice)  
        {  
            case 1:  
            insertion_beginning();  
            break;  
            case 2:  
            insertion_last();  
            break;  
            case 3:  
            insertion_specified();  
            break;  
            case 4:  
            deletion_beginning();  
            break;  
            case 5:  
            deletion_last();  
            break;  
            case 6:  
            deletion_specified();  
            break;  
            case 7:  
            search();  
            break;  
            case 8:  
            display();  
            break;  
            case 9:  
            exit(0);  
            break;  
            default:  
            printf("Please enter valid choice..");  
        }  
    }  
}  
void insertion_beginning()  
{  
   struct node *ptr;   
   int item;  
   ptr = (struct node *)malloc(sizeof(struct node));  
   if(ptr == NULL)  
   {  
       printf("\nOVERFLOW");  
   }  
   else  
   {  
    printf("\nEnter Item value");  
    scanf("%d",&item);  
      
   if(head==NULL)  
   {  
       ptr->next = NULL;  
       ptr->prev=NULL;  
       ptr->data=item;  
       head=ptr;  
   }  
   else   
   {  
       ptr->data=item;  
       ptr->prev=NULL;  
       ptr->next = head;  
       head->prev=ptr;  
       head=ptr;  
   }  
   printf("\nNode inserted\n");  
}  
     
}  
void insertion_last()  
{  
   struct node *ptr,*temp;  
   int item;  
   ptr = (struct node *) malloc(sizeof(struct node));  
   if(ptr == NULL)  
   {  
       printf("\nOVERFLOW");  
   }  
   else  
   {  
       printf("\nEnter value");  
       scanf("%d",&item);  
        ptr->data=item;  
       if(head == NULL)  
       {  
           ptr->next = NULL;  
           ptr->prev = NULL;  
           head = ptr;  
       }  
       else  
       {  
          temp = head;  
          while(temp->next!=NULL)  
          {  
              temp = temp->next;  
          }  
          temp->next = ptr;  
          ptr ->prev=temp;  
          ptr->next = NULL;  
          }  
             
       }  
     printf("\nnode inserted\n");  
    }  
void insertion_specified()  
{  
   struct node *ptr,*temp;  
   int item,loc,i;  
   ptr = (struct node *)malloc(sizeof(struct node));  
   if(ptr == NULL)  
   {  
       printf("\n OVERFLOW");  
   }  
   else  
   {  
       temp=head;  
       printf("Enter the location");  
       scanf("%d",&loc);  
       for(i=0;i<loc;i++)  
       {  
           temp = temp->next;  
           if(temp == NULL)  
           {  
               printf("\n There are less than %d elements", loc);  
               return;  
           }  
       }  
       printf("Enter value");  
       scanf("%d",&item);  
       ptr->data = item;  
       ptr->next = temp->next;  
       ptr -> prev = temp;  
       temp->next = ptr;  
       temp->next->prev=ptr;  
       printf("\nnode inserted\n");  
   }  
}  
void deletion_beginning()  
{  
    struct node *ptr;  
    if(head == NULL)  
    {  
        printf("\n UNDERFLOW");  
    }  
    else if(head->next == NULL)  
    {  
        head = NULL;   
        free(head);  
        printf("\nnode deleted\n");  
    }  
    else  
    {  
        ptr = head;  
        head = head -> next;  
        head -> prev = NULL;  
        free(ptr);  
        printf("\nnode deleted\n");  
    }  
  
}  
void deletion_last()  
{  
    struct node *ptr;  
    if(head == NULL)  
    {  
        printf("\n UNDERFLOW");  
    }  
    else if(head->next == NULL)  
    {  
        head = NULL;   
        free(head);   
        printf("\nnode deleted\n");  
    }  
    else   
    {  
        ptr = head;   
        if(ptr->next != NULL)  
        {  
            ptr = ptr -> next;   
        }  
        ptr -> prev -> next = NULL;   
        free(ptr);  
        printf("\nnode deleted\n");  
    }  
}  
void deletion_specified()  
{  
    struct node *ptr, *temp;  
    int val;  
    printf("\n Enter the data after which the node is to be deleted : ");  
    scanf("%d", &val);  
    ptr = head;  
    while(ptr -> data != val)  
    ptr = ptr -> next;  
    if(ptr -> next == NULL)  
    {  
        printf("\nCan't delete\n");  
    }  
    else if(ptr -> next -> next == NULL)  
    {  
        ptr ->next = NULL;  
    }  
    else  
    {   
        temp = ptr -> next;  
        ptr -> next = temp -> next;  
        temp -> next -> prev = ptr;  
        free(temp);  
        printf("\nnode deleted\n");  
    }     
}  
void display()  
{  
    struct node *ptr;  
    printf("\n printing values...\n");  
    ptr = head;  
    while(ptr != NULL)  
    {  
        printf("%d\n",ptr->data);  
        ptr=ptr->next;  
    }  
}   
void search()  
{  
    struct node *ptr;  
    int item,i=0,flag;  
    ptr = head;   
    if(ptr == NULL)  
    {  
        printf("\nEmpty List\n");  
    }  
    else  
    {   
        printf("\nEnter item which you want to search?\n");   
        scanf("%d",&item);  
        while (ptr!=NULL)  
        {  
            if(ptr->data == item)  
            {  
                printf("\nitem found at location %d ",i+1);  
                flag=0;  
                break;  
            }   
            else  
            {  
                flag=1;  
            }  
            i++;  
            ptr = ptr -> next;  
        }  
        if(flag==1)  
        {  
            printf("\nItem not found\n");  
        }  
    }     
          
}