C++ implementation of the DoubleLinkedList

//DoubleLinkedList.h



#ifndef DOUBLELINKEDLIST_H
#define DOUBLELINKEDLIST_H


struct node{
char *load;
node *next;
node *prev;
};
class DoubleLinkedList
{
    public:
    node *head;
    DoubleLinkedList();
    void addAtHead(char *str);
    void addAtTail(char *str);
    void addAtIndex(char *str,int index);
    void deleteAtHead();
    void deleteAtTail();
    void deleteAtIndex(int index);
    int getLength();
    void printAllValues();
    protected:
    private:
};


#endif // DOUBLELINKEDLIST_H

//DoubleLinkedList.cpp

#include "include/DoubleLinkedList.h"

#include <iostream>

#include "malloc.h"

using namespace std;

DoubleLinkedList::DoubleLinkedList()

{

    head = NULL;

}

void DoubleLinkedList::addAtHead(char *str){

    addAtIndex(str,0);

}

void DoubleLinkedList::addAtTail(char *str){

    addAtIndex(str,getLength());

}

void DoubleLinkedList::addAtIndex(char *str,int index){

   node *ref = head;

   if(index == 0){

       node *newVal = (node *)malloc(sizeof(node));

       newVal->load = str;

       newVal->next = head;

       newVal->prev = NULL;

       head = newVal;

       return;

   }

   int i=0;

   while(ref!= NULL){

    if(i == index - 1){

       node *newVal = (node *)malloc(sizeof(node));

       newVal->load = str;

       newVal->next = ref->next;

       newVal->prev = ref;

       ref->next = newVal;

       if(newVal->next != NULL)

       newVal->next->prev = newVal;

       return;

    }

    i++;

    ref = ref->next;

   }

   int no = getLength();

   cout<<"\nError: Invalid index this linked list has only "<<no<<" element(s)";

}

void DoubleLinkedList::deleteAtHead(){

    deleteAtIndex(0);

}

void DoubleLinkedList::deleteAtTail(){

    deleteAtIndex(getLength()-1);

}

void DoubleLinkedList::deleteAtIndex(int index){

   node *ref = head;

   if(index == 0){

        if(head != NULL){

            head = head ->next;

            head->prev = NULL;

            cout<<"\nThe element at index "<<index<<" with value "<<ref->load<<" is deleted";

            free(ref);

        }

       return;

   }

   int i=0;

   while(ref!= NULL){

    if(i == index - 1){

       if(ref->next != NULL){

       node* r = ref->next;

       ref->next = r->next;

       if(ref->next != NULL)

       ref->next->prev = ref;

       cout<<"\nThe element at index "<<index<<" with value "<<r->load<<" is deleted";

       free(r);

       }

       return;

    }

    i++;

    ref = ref->next;

   }

   int no = getLength();

   cout<<"\nError: Invalid index this linked list has only "<<no<<" element(s)";

}

int DoubleLinkedList :: getLength(){

    node *ref = head;

    int i=0;

    while(ref != NULL){

    i++;

    ref = ref->next;

    }

    return i;

}

void DoubleLinkedList :: printAllValues(){

    node *ref = head;

    int i=0;

    while(ref != NULL){

    cout<<"\nElement "<<i++<<" : "<<ref->load;

    ref = ref->next;

    }

}

int main(){

 DoubleLinkedList list;

 list.addAtHead("test1");

 list.addAtHead("test2");

 list.addAtHead("test3");

 list.addAtTail("test4");

 list.addAtIndex("test5",2);

 list.printAllValues();

 list.deleteAtHead();

 list.printAllValues();

 list.deleteAtTail();

 list.printAllValues();

 list.deleteAtIndex(1);

 list.printAllValues();

}