linkedList.c

// Program for displaying, inserting and deleting elements to doubly linked list.
#include<stdio.h>  
#include<stdlib.h>  
struct node  
{  
    struct node *prev;  
    struct node *next;  
    int data;  
};  
struct node *head;  
  
void insertion_specified();   
void deletion_specified();  
void display();  
void search();  
void main ()  
{  
int choice =0;  
    while(choice != 6)  
    {  
        printf("\n*********Main Menu*********\n");  
        printf("\nChoose one option from the following list ...\n");  
        printf("\n===============================================\n");  
        printf("\n1.Insert at any random location\n2.Delete the node after the given data\n3.Search\n4.Show\n5.Exit\n");  
        printf("\nEnter your choice?\n");  
        scanf("\n%d",&choice);  
        switch(choice)  
        {  
            case 1:  
            insertion_specified();  
            break;  
            case 2:  
            deletion_specified();  
            break;  
            case 3:  
            search();  
            break;  
            case 4:  
            display();  
            break;  
            case 5:  
            exit(0);  
            break;  
            default:  
            printf("Please enter valid choice..");  
        }  
    }  
}  


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_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");  
        }  
    }     
          
}