linked list

#include <iostream>
#include <stdlib.h>

using namespace std;

struct merk
{
    string namaMerk;
    int stock;
};

struct data
{
    string namaBarang;
    string deskripsiBarang;
    int harga;
    merk merkBarang;
    data *next;
    data *prev;
};

data *bantu,*bantu1,*baru,*awal=NULL,*akhir=NULL;
int total=0;
int input;

void inputData();
void showData();
void deleteData();

int main()
{
    char prompt;
    int pil;


    do
    {
        system("cls");
        cout << "Total data = " << total << endl;
        cout << "\nPilihan!!!" << endl;
        cout << "1. Input data" << endl;
        cout << "2. show data" << endl;
        cout << "3. Delete data" << endl;
        cout << "4. Done" << endl;

        cout << "\n\nMasukkan pilihan = ";
        cin >> pil;

        switch(pil)
        {
        case 1:
            {
                do
                {
                    inputData();
                    cout << "ingin input lagi? (y/n)";
                    cin >> prompt;
                }while (prompt=='y');
                system("pause");
                break;
            }
        case 2:
            {
                showData();
                system("pause");
                break;
            }
        case 3:
            {
                deleteData();
                system("pause");
                break;
            }
        }
    }while (pil<4);

    return 0;
}

void inputData()
{
    baru=new data;
    cout << "\nMasukkan nama barang = ";
    cin >> baru->namaBarang;
    cout << "Masukkan deskripsi barang = ";
    cin >> baru->deskripsiBarang;
    cout << "Masukkan merk barang = ";
    cin >> baru->merkBarang.namaMerk;
    cout << "Masukkan jumlah barang yang tersedia = ";
    cin >> baru->merkBarang.stock;
    cout << "Masukkan harga barang = ";
    cin >> baru->harga;
    baru->next=baru->prev=NULL;

    cout << "Tambahkan pada data index ke = ";
    cin >> input;

    if (awal==NULL)
    {
        awal=akhir=baru;
    }
    else
    {
        if (input<=0)
        {
            baru->next=awal;
            awal->prev=baru;
            awal=baru;
        }
        else if(input>=total)
        {
            akhir->next=baru;
            baru->prev=akhir;
            akhir=baru;
        }
        else
        {
            bantu=awal;
            for(int i=0;i<input-1;i++)
            {
                bantu=bantu->next;
            }
            baru->next=bantu->next;
            bantu->next->prev=baru;
            baru->prev=bantu;
            bantu->next=baru;
        }
    }
    total++;
}

void showData()
{
    baru=awal;
    while(baru!=NULL)
    {
        cout << "\nNama barang = " << baru->namaBarang;
        cout << "\nDeskripsi barang = " << baru->deskripsiBarang;
        cout << "\nMerk barang = " << baru->merkBarang.namaMerk;
        cout << "\nJumlah barang yang tersedia = " << baru->merkBarang.stock;
        cout << "\nHarga barang = " << baru->harga << endl;
        cout << endl;
        baru=baru->next;
    }
}

void deleteData()
{
        if (total>0)
        {
            if (awal==akhir || total==1)
            {
                delete awal;
                awal=akhir=NULL;
            }
            else
            {
                cout << "\nHapus index ke = ";
                cin >> input;

                if (input<=1)
                {
                    bantu=awal->next;
                    bantu->prev=NULL;
                    delete awal;
                    awal=bantu;
                }
                else if(total>=total-1)
                {
                    bantu=akhir->prev;
                    bantu->next=NULL;
                    delete akhir;
                    akhir=bantu;
                }
                else
                {
                    bantu=awal;
                    for(int i=0;i<input-1;++i)
                    {
                        bantu=bantu->next;
                    }
                    bantu1=bantu->next->next;
                    delete bantu->next;
                    bantu->next=bantu1;
                    bantu1->prev=bantu;
                }
            }
            cout << "\nData telah di hapus" << endl;
            total--;
        }
        else
        {
            cerr << "\nMaaf data masih kosong!!" << endl;;
        }
}