Doubly Linked List

 Doubly Linked List

struct Node

{

int element;

struct Node *Next;

struct Node *Prev;

};

typedef struct Node *Position, *List;

//typedef PtrToNode Position;

//typedef PtrToNode List;

Position Find(int x, List L)

{

Position P;

P = L->Next;

while(P!=NULL && P->element!=x)

P = P->Next;

return P;

}

void Delete(int x, List L)

{

Position P, Tmpcell;

P=L->Next;

while(P->element!=x)

P=P->Next;

if(P!=NULL)

{

Tmpcell = P;

P->Prev->Next = Tmpcell->Next;

P->Next->Prev = Tmpcell->Prev;

free(Tmpcell);

}

}

void InsertAtBegining(int x, List L)

{

Position Tmpcell;

Tmpcell = (struct Node *)malloc(sizeof(struct Node));

if(Tmpcell == NULL)

printf("Error. Unable to allocate memory\n");

Tmpcell->element = x;

Tmpcell->Next = L->Next;

Tmpcell->Prev = L;

L->Next = Tmpcell;

}

void InsertAtEnd(int x, List L)

{

Position P, Tmpcell;

P = L;

Tmpcell = (struct Node *)malloc(sizeof(struct Node));

if(Tmpcell == NULL)

printf("Error. Unable to allocate memory\n");

while(P->Next!=NULL)

P = P->Next;

Tmpcell->element = x;

Tmpcell->Next = P->Next;

Tmpcell->Prev = P;

P->Next = Tmpcell;

}

void InsertAtPosition(int x, int index, List L)

{

Position P, Tmpcell;

int i=1;

P=L;

Tmpcell = (struct Node *)malloc(sizeof(struct Node));

if(Tmpcell == NULL)

printf("Error. Unable to allocate memory\n");

while(i<index)

{

P = P->Next;

i++;

}

Tmpcell->element = x;

Tmpcell->Next = P->Next;

Tmpcell->Prev = P;

P->Next = Tmpcell;

}

List Create()

{

List L;

L = (struct Node *)malloc(sizeof(struct Node));

if(L==NULL)

printf("Error. Unable to allocate mempry.\n");

else

{

L->element = -1;

L->Next = NULL;

L->Prev = NULL;

}

return L;

}