Double Linked List in C++ - a blog of a local hero wannabe

This is double linked list example :

#include <conio.h>
#include <iostream.h>

typedef struct TNode {
    int data;
    TNode *next;
    TNode *prev;
}TNode;

TNode *head, *tail;

void init() {
    head = NULL;
    tail = NULL;
}

bool isEmpty() {
    if (tail == NULL) return true;
   else return false;
}

/*insert depan*/
void add_at_front () {
    TNode *baru;
   baru = new TNode;
   cout <<"Silahkan masukkan Data : ";
   cin >> baru->data;
   baru->next = NULL;
   baru->prev = NULL;
   if (isEmpty()==true)
       head = baru;
      tail = head;
      head->next = NULL;
      head->prev = NULL;
      tail->next = NULL;
      tail->prev = NULL;
   } else {
       baru->next = head;
      head->prev = baru:
      head = baru;
   }
}

/*tambah data di belakang*/
void add_at_end() {
        TNode *baru;
      baru = new TNode;
      cout << "Silahkan masukkan Data : ";
      cin >> baru -> data;
      baru->next = NULL;
      baru->prev = NULL;

      if (isEmpty() == true) {
          head = baru;
         tail = head;
         head->next = NULL;
         head->prev = NULL;
         tail->next = NULL;
         tail->prev = NULL;
      } else {
          tail->next = baru;
         baru->prev=tail;
         tail=baru;
         tail->bext=NULL;
      }
}

/*hapus simpul dari depan*/
void del_at_front() {
    TNode *hapus;
   int d;
   if (isEmpty() == false) {
       if (head->next !=NULL) {
      hapus = head;
      d = hapus->data;
      head = head->next;
      head->prev=NULL;
      delete hapus;
    } else {
        d = head->data;
      head = NULL;
      tail = NULL;
    }
    cout << d << "terhapus \";
} else {
    cout << "Masih kosong \n";
}
}

void del_at_end() {
        TNode *hapus;
      int d;
      if (isEmpty() == false) {
          if (head->next != NULL){
                  hapus = tail;
               d=tail->data;
               tail = tail->prev;
               tail = next = NULL;
               delete hapus;
          } else {
                  d= head->data;
               head = NULL;
               tail = NULL;
          }
          cout << d << "terhapus \n";
      } else {
          cout << "Data kosong . .\n";
      }
}

/*hapus semua simpul*/
void clear () {
    TNode *bantu, *hapus;
   bantu = head;
   while (bantu !=NULL) {
       hapus = bantu;
      bantu=bantu->next;
      delete hapus;
   }
   head = NULL;
   tail = NULL;
}

/*menampilkan simpul*/
void display () {
    TNode *bantu;
   bantu = head;
   if (isEmpty()==false) {
       while(bantu!=tail->next) {
          cout << bantu->data << "" ;
         bantu = bantu->next;
      }
      cout << endl;
   }else {
       cout << "Data Kosong";
   }
}

void main () {
    int data;
   int pil;
   do {
           cout << "1. Tambah Depan\n";
         cout << "2. Tambah Belakang\n";
         cout << "3. Hapus Depan\n";
         cout << "4. Hapus Belakang\n";
         cout << "5. Tampil\n";
         cout << "6. Hapus semua Data\n";
         cout << "7. Exit\n";
         cout << "pilihan : ";
         cin >> pil;
         clrscr ();
         switch (pil) {
             case 1: add_at_front(); break;
            case 2: add_at_end(); break;
            case 3: del_at_front(); break;
            case 4: del_at_end(); break;
            case 5: display(); break;
            case 6: clear(); break;
         }
         getch ();
     }while (pil !=7);
;