doubly_linked

#include <iostream>

#define ENABLE_DEBUG
using namespace std;

struct Node{
  Node* prev;
  int data;
  Node* link;
};

//Prototypes
void insertAtBeg(struct Node** head,int data);
void append(struct Node** head, int data);
void insertAtPos(int pos,struct Node** head, int data);


void insertAtBeg(struct Node** head,int data){
    Node* temp1 = (Node*)malloc(sizeof(Node));
    temp1->prev = NULL;
    temp1->data = data;
    temp1->link = NULL;
    Node* temp;
    temp = *head;
    if(temp == NULL){
        *head = temp1;
        return;
    }
// since we are placing node at beginning previous link is null so no need 
//to mention temp1->prev = NULL
    temp1->link = temp;
    temp->prev = temp1;
    *head = temp1;
    #ifdef ENABLE_DEBUG
        cout << "Inserted at Beginning";
    #endif
    return;
}

void append(struct Node** head, int data){
    Node* temp1;
    temp1->prev = NULL;
    temp1->data = data;
    temp1->link = NULL;
    Node* temp;
    temp = *head;
    if(temp == NULL){
        *head = temp1;
        return;
    }
    while(temp->link != NULL){
        temp = temp->link;
    }
    temp1->prev = temp;
    temp->link = temp1;
    
    #ifdef ENABLE_DEBUG
        cout << "Inserted at End";
    #endif
    
    return;
}

int count(struct Node* head){
    if(head == NULL){
        return 0;
    }
    return 1 + count(head);
}

void insertAtPos(int pos,struct Node** head, int data){
    Node* temp1;
    if(temp1 != NULL){
            temp1->prev = NULL;
            temp1->data = data;
            temp1->link = NULL;
            if(pos<1 || pos > count(*head)){
                cout << "Insertion not possible";
                return;
            }
            Node* temp;
            temp = *head;
            if(temp == NULL && pos ==1){
                cout << "A successful Insertion";
                *head = temp1;
            }
            int c = 1;
            cout << "Insertion at Given position starts here";
            while(temp != NULL && pos>=c){
                if(pos == c){
                    temp1->prev = temp->prev;
                    temp1->link = temp;
                    temp->prev = temp1;
                    return;
                }
                temp = temp->link;
            }
            cout << "Inserted at given position";
    }
    else{
        cout << "MEMORY FULL";
    }
}

void print(struct Node* head){
    #ifdef ENABLE_DEBUG
        cout << "Printing the linked List: \n";
    #endif
    Node* temp = head;
    while(temp != NULL){
        cout << temp->data << "\t";
        temp = temp->link;
    }
    cout << "\n";
    return;
}

int main() {
    
    Node* head;
    head = NULL;
// if we pass head directly it will be passed to insertAtBeg as Call By Value
// so it will not modify original thing its just a copy of original Linked List
    insertAtBeg(&head,10);
    cout << "About to print";
    print(head);
    append(&head,5);
    insertAtPos(2,&head,15);
    append(&head,1);
    print(head);// 10 15 5 1
    
    return 0;
}