// DSTC --- DLIST.H -- DOUBLE LINK LIST ... #include <stdio.h>
#include <stdlib.h>
typedef struct nd
{
int info;
struct nd *next;
struct nd *prev;
}Node;
typedef struct {
Node *start;
}Dlinklist; Dlinklist * GetDlinklist()
{
Dlinklist *temp;
temp=(Dlinklist *)malloc(sizeof(Dlinklist));
temp->start=NULL;
return temp;
} Node * GetNode()
{
Node *n;
n=(Node *)malloc(sizeof(Node));
n->next=NULL;
n->prev=NULL;
return n;
} int empty(Dlinklist *l)
{
if(l->start==NULL)
return 1;
else
return 0;
} //Obtaining address of last node
Node * LastNode(Dlinklist *l)
{
Node *t;
if(empty(l))
return NULL; t=l->start;
while(t->next!=NULL)
t=t->next;
return t;
}
//Count number of nodes
int CountNodes(Dlinklist *l)
{
int c=0;
Node *t; t=l->start;
while(t)
{
c++;
t=t->next;
}
return c;
} // Inserting a new node in beginning
void InsBeg(Dlinklist *l, int i)
{
Node *n;
n=GetNode();
n->info=i;
if(!empty(l))
{
n->next=l->start;
l->start->prev=n;
}
l->start=n;
} // Deleting a node from beginning
int DelBeg(Dlinklist *l)
{
Node *t;
if(empty(l))
{
printf("Dlinklist already empty\n");
return 0; //unsussefull operation
}
t=l->start;
l->start=t->next;
l->start->prev=NULL;
free(t);
return 1; //successfull operation
} // Inserting a new node at end
void InsEnd(Dlinklist *l, int i)
{
Node *n;
Node *t;
n=GetNode();
n->info=i;
if(empty(l))
l->start=n;
else
{
//first of all we will go to last node
t=LastNode(l);
t->next=n;
n->prev=t;
}
} // Deleting a node from end
int DelEnd(Dlinklist *l)
{
Node *t;
//if linklist is empty
if(empty(l))
{
printf("Dlinklist already empty\n");
return 0; //unsussefull operation
} t=l->start;
//if linklist contain only one node
if(l->start->next==NULL)
{
l->start=NULL;
free(t);
return 1;
} //if linklist contains more than one node
while(t->next!=NULL)
t=t->next; t->prev->next=NULL;
free(t);
return 1; //successfull operation
} // Inserting a new node at specific positon int InsPos(Dlinklist *l, int i, int pos)
{
Node *n;
Node *t; if(pos>CountNodes(l))
{
printf("Syntax error ... this many nodes does not exist");
return 0; //unsuccessull operation
} //if node is to be inserted at first position
if(pos==1)
{
InsBeg(l,i);
return 1;
} n=GetNode();
n->info=i; //obtain a node just before the inserted position
t=l->start;
while(pos>2)
{
t=t->next;
pos--;
}
n->next=t->next;
t->next->prev=n;
t->next=n;
n->prev=t;
return 1;
} // Deleting a node at specific position
int DelPos(Dlinklist *l,int pos)
{
Node *t;
//check number of nodes
if(pos>CountNodes(l))
{
printf("Syntax error ... this many nodes does not exist");
return 0; //unsuccessfull operation
}
//if node is to be deleted from first position
if(pos==1)
{
DelBeg(l);
return 1;
} //obtain a node to be deleted
t=l->start;
while(pos>=2)
{
t=t->next;
pos--;
} t->prev->next=t->next;
t->next->prev=t->prev;
free(t);
return 1;
} void Displist(Dlinklist *l)
{
Node *t;
int i=1;
t=l->start;
printf("\n------------------Link list details----------------------\n");
printf("Total nodes are: %d \n\n", CountNodes(l));
while(t)
{
printf("Node number %d is: %d\n", i, t->info);
i++;
t=t->next;
}
printf("\n---------------------------------------------------------\n");
} | 
