Double-linked list implementation from programming class

DoubleList.cpp

#include "DoubleList.h"

struct DoubleListElement
{
	double value = 0.0;
	DoubleListElement* prev = nullptr;
	DoubleListElement* next = nullptr;
};

struct DoubleList
{
	DoubleListElement* head = nullptr;
	DoubleListElement* tail = nullptr;
	unsigned size = 0;
};

DoubleList *createDoubleList()
{
	return new DoubleList;
}

double value(DoubleListElement* position)
{
	return position->value;
}

void deleteDoubleList(DoubleList *&list) {
	DoubleListElement* next = list->head;

	while (next != nullptr) {

		// временное хранилище следующего элемента
		DoubleListElement* temp = next->next;

		delete next;
		next = temp;
	}

	delete list;
	list = nullptr;
}

void addElement(double newValue, DoubleList* list, DoubleListElement* prevElement) {
	// у нас есть указатель на элемент ПЕРЕД
	// можем узнать элемент, стоящий ПОСЛЕ

	DoubleListElement* nextElement = prevElement->next;

	DoubleListElement* newElement = new DoubleListElement;

	// создание нового элемента
	newElement->value = newValue;
	newElement->prev = prevElement;
	newElement->next = nextElement;

	// меняем предыдущий
	prevElement->next = newElement;

	// меняем последующий
	if (nextElement != nullptr) {
		nextElement->prev = newElement;
	}
	else {
		list->tail = newElement;
	}

	list->size += 1;
}

void addNewHead(double newValue, DoubleList* list) {

	DoubleListElement* newElement = new DoubleListElement;

	//создани новую голову
	newElement->value = newValue;
	newElement->prev = nullptr;
	newElement->next = list->head;

	//список указывает на новую голову
	list->head = newElement;

	if (list->tail == nullptr) {
		list->tail = newElement;
	}

	list->size += 1;
}

Position getTail(DoubleList* list)
{
	return list->tail;
}

Position getHead(DoubleList* list)
{
	return list->head;
}

bool isInTheEnd(Position a)
{
	return a == nullptr;
}

Position getNext(Position a)
{
	return a->next;
}

DoubleList.h

#pragma once

struct DoubleListElement;

typedef DoubleListElement* Position;

struct DoubleList;

DoubleList *createDoubleList();
void deleteDoubleList(DoubleList *&list);

// Returns value by given position.
double value(Position position);

double valueAt(DoubleList* list, int index); //
void addElementAt(double value, DoubleList* list, int index); //

void addElement(double newValue, DoubleList* list, Position pasteBefore);

void addNewHead(double newValue, DoubleList* list);

void deleteElement(Position index);
Position getHead(DoubleList* list);
Position getTail(DoubleList* a);
bool isInTheEnd(Position a);
Position getNext(Position a);

main.cpp

#include "stdafx.h"
#include <iostream>
#include "DoubleList.h"

using namespace std;

int main()
{
	DoubleList *sample = createDoubleList();
	addNewHead(0.0, sample);
	for (double i = 1.0; i < 3.0; i++)
	{
		addElement(i, sample, getTail(sample));
	}

	for (Position i = getHead(sample); !isInTheEnd(i); i = getNext(i))
	{
		cout << value(i) << " ";
	}

	deleteDoubleList(sample);
	return 0;
}