I wrote the following code, can anyone tell me why is it not working, I was unable to find a reason...

//*************************SERIOUS PROBLEM, NOT WORKING******************
Code:
//DOUBLY LINKED LIST

#include<stdio.h>
#include<stdlib.h>

struct dll
{
int info;
struct dll *next;
struct dll *prev;
};
struct dll *head = NULL, *tail = NULL, *temp;

void append();
void insafter();
void delete();
void display();

void main()
{
int choice;
do
{
printf("Enter your choice:\n");
printf("1.Append Node\n2.Insert After a Node\n3.Delete the First Node\n4.Display\n5.Exit");
scanf("%d", &choice);
switch(choice)
	{
	case 1:
		append();
		break;
	case 2:
		insafter();
		break;
	case 3:
		delete();
		break;
	case 4:
		display();
	case 5:
		exit(1);
	default:
	printf("Invalid choice!\n");
	}
}while(choice!=4);
}

void append()
{
int x;
printf("Enter element you wish to push\n");
scanf("%d", &x);
temp->info = x;
if(head==tail && head==NULL)
	{
	temp = head;
	temp->next = temp;
	temp->prev = NULL;
	}
else
	{
	tail->next = temp;
	temp->prev = tail;
	}
tail = temp;
temp->next = NULL;
}

void insafter() //I assume user inputs this option after he has made a list, no condition check for empty list
{
int x, added_item;
printf("Enter the information of the node after which you want to insert your new node\n");
scanf("%d", &x);
temp = head;
while(temp!=NULL)
	{
	while(temp->info!=x)
	temp= temp->next;
	}//now we have the node temp after which we insert our node
printf("Enter item to be added\n");
scanf("%d", &added_item);
struct dll *p;
p->info = added_item;
p->next = temp->next;
p->prev = temp;
temp->next = p;
}

void delete() //allows deleting only from head
{
temp = head;
if(head==NULL)
printf("List empty, nothing to delete\n");
else
printf("Deleted element: %d", temp->info);
head = head->next;
free(temp);
}

void display()
{
temp = head;
if(head==NULL)
printf("Doubly Linked List empty\n");
else
while(temp!=NULL)
	{
	printf("%d", temp->info);
	temp = temp->next;
	}
}

Last edited by shabbir; 14Apr2010 at 21:08.. Reason: Code blocks