func

#include <types.h>
#include <functions.h>
#include <iostream>

using namespace std;

void addToStart ( listNode * &list, listNode * PNew)
{
    if(list == NULL){
        PNew->next = NULL;
        PNew->prev = NULL;
        list = PNew;
        cout << "Элемент был добавлен." << endl;
        return;
    }
    PNew->prev = NULL;
    list->prev = PNew;
    PNew->next = list;
    list = PNew;
    cout << "Элемент был добавлен." << endl;
    return;
}

void addToEnd ( listNode *&list, listNode *PNew)
{
    if(list == NULL){
        PNew->next = NULL;
        PNew->prev = NULL;
        list = PNew;
        cout << "Элемент был добавлен." << endl;
        return;
    }
    PNew->next = NULL;
    listNode *wp = list;
    listNode *prev = NULL;
    while(wp != NULL){
        prev = wp;
        wp = wp->next;
    }
    prev->next = PNew;
    PNew->prev = prev;
    cout << "Элемент был добавлен." << endl;
    return;
}

void addToSort(listNode *&list, listNode *PNew)
{
     PNew->next = NULL;
     PNew->prev = NULL;

     if (list == NULL || PNew->number <= list->number)
     {
             PNew->next = list;
             if ( list != NULL )
                     list->prev = PNew;
             list = PNew;
             return;
     }

     listNode * wp = list->next;
     listNode * prev = list;

     if ( wp != NULL)
             while (wp != NULL && wp->number < PNew->number)
             {
                     prev = wp;
                     wp = wp->next;
             }

     prev->next = PNew;
     PNew->prev = prev;
     PNew->next = wp;
     if(wp != NULL && wp->next != NULL)
             wp->next->prev = PNew;
}

void printList ( listNode *list )
{
        if (list == NULL)
        {
                cout << " Список пустой! \n";
                return;
        }
        listNode *wp = list;
        while ( wp != NULL)
        {
                cout << wp->number << " ";
                wp = wp->next;
        }
        cout << endl << endl;
}

void delFromSort ( listNode *&list, int num)
{
    listNode *wp = list;

    while (wp != NULL)
    {
            if (num != wp->number)
            {
                    wp = wp->next;
            }

            else
            {
                    listNode *pDel = wp;
                    if ( wp->prev != NULL )
                            wp->prev->next = wp->next;
                    else
                            list = wp->next;

                    if ( wp->next != NULL )
                            wp->next->prev = wp->prev;
                    delete pDel;
            }
    }
}

void delList ( listNode *&list )
{
        listNode *wp = list;

        while ( wp != NULL)
        {
                listNode *pDel = wp;
                wp = wp->next;
                delete pDel;
        }
        list = NULL;
}

void specEl ( listNode *&list )
{
        if (list ==  NULL || list->next == NULL  )
            return;

    listNode *prev1 = NULL;
    listNode *prev2 = NULL;
    listNode *wp = list;
    listNode *fol1 = NULL;
    listNode *fol2 = NULL;
    int sumNext = 0;
    int sumPrev = 0;



    while ( wp )
    {
        prev1 = wp->prev;
                fol1 = wp->next;

                if (prev1)
                        prev2 = prev1->prev;
                else
                        prev2 = NULL;

                if (fol1)
                        fol2 = fol1->next;
                else
                        fol2 = NULL;

                if (fol2)
                        sumNext = fol1->number + fol2->number;
                else if (fol1)
                        sumNext = fol1->number;

                if (prev1 && prev2)
                        sumPrev = prev1->number + prev2->number;
                else if (prev1)
                        sumPrev = prev1->number;

                if (sumNext > sumPrev)
                {
                        cout << "Элемент, удовлетворяющий условия: " << wp->number << endl
                         << "Cумма двух предыдущих элементов: " << sumPrev << endl;
                    cout << "Cумма двух последующих элементов: " << sumNext << endl << endl;
                }

                sumNext = 0;
                sumPrev = 0;

                wp = wp->next;
        }
}

void delEl (listNode *&list)
{
    if (list == NULL)
            return;

    listNode *wp = list;

            while (wp->next != NULL)
            {
                    if (wp->next->number %2 == 1)
                    {
                        listNode *pDel = wp;
                        if ( wp->prev != NULL )
                                wp->prev->next = wp->next;
                        else
                                list = wp->next;

                        if ( wp->next != NULL )
                                wp->next->prev = wp->prev;
                        delete pDel;
                    }
                    else
                        wp = wp->next;
            }

}