DeleteDLL.c

#include <stdio.h>
#include <stdlib.h>
struct Node
{
    struct Node *prev;
    int data;
    struct Node *next;
} *first=NULL;
void create(int A[], int n)
{
    struct Node *t,*last;
    int i;
    first=(struct Node *)malloc(sizeof(struct Node));
    first->data=A[0];
    first->prev=first->next=NULL;
    last=first;
    for(i=1;i<n;i++)
    {
        t=(struct Node *)malloc(sizeof(struct Node));
        t->data=A[i];
        t->next=last->next;
        t->prev=last;
        last->next=t;
        last=t;
    }
}
void Display(struct Node *p)
{
    while(p)
    {
        printf("%d\t",p->data);
        p=p->next;
    }
    printf("\n");
}
int Length(struct Node *p)
{
    int len=0;
    while(p)
    {
        len++;
        p=p->next;
    }
    return len;
}
void Insert(struct Node *p, int index, int x)
{
    struct Node *t;
    int i;
    if(index<0 || index> Length(p))
        return;
    if(index==0)
    {
        t=(struct Node *)malloc(sizeof(struct Node));
        t->data=x;
        t->prev=NULL;
        t->next=first;
        first->prev=t;
        first=t;
    }    

else
{
    for(i=0;i<index-1;i++)
        p=p->next;
    t=(struct Node *)malloc(sizeof(struct Node));
    t->data=x;
    t->prev=p;
    t->next=p->next;
    if(p->next)
        p->next->prev=t;
    p->next=t;
}
}
int Delete(struct Node *p, int index)
{
    struct Node *q;
    int x=-1,i;
    if(index<0 || index> Length(p))
        return -1;
    if (index==1)
    {
        first=first->next;
        if(first)first->prev=NULL;
        x=p->data;
        free(p);
    }
    else
    {
    for(i=0;i<index-1;i++)
        p=p->next;
    p->prev->next=p->next;
    if(p->next)
        p->next->prev=p->prev;
    x=p->data;
    free(p);
    }
    return x;
}
int main()
{
    int A[]={10,20,30,40,50};
    create(A,5);
    //Insert(first,2,25);
    Delete(first,3);
    printf("\nLength is :%d\n",Length(first));
    Display(first);
    return 0;
}