Mirsaid Aripov, Nurillo Otaxanov

10.6-listing. Tugunni ro`yxatdan o`chirish

procedure TForm1.Button3Click(Sender: TObject);

var curr:TPStudent;  joriy, tekshirilayotgan tugun

pre: TPStudent;  avvalgi tugun

found:boolean;  TRUE – o`chiriladigan tugun ro`yxatda bor

begin

if head  NIL then

begin

MessageDlg('Ro`yxat bo`sh!', mtError,[mbOk],0);

Exit;

end;

curr : head;  joriy tugun - birinchi tugun

pre:NIL;  undan oldin tugunlar yo`q

found : FALSE;

 O`chirilishi talab qilingan tugunni topish

while (curr <> NIL) and (not found) do

begin

if (curr^.f_name  Edit1.Text) and (curr^.l_name  Edit2.Text)

then found : TRUE  kerakli tugun topildi

else  navbatdagi tugunga

begin pre : curr; curr : curr^.next; end;

end;

if found then begin  kerakli tugun topildi

if MessageDlg('tugun ro`yxatdan o`chiriladi!',

mtWarning,[mbOk,mbCancel],0) <> mrYes

then Exit;

 tugun o`chirilmoqda

if pre  NIL then head : curr^.next

ro`yxatdagi birinchi tugun o`chirilmoqda

else pre^.next : curr.next;

Dispose(curr);

MessageDlg('Tugun'  #13 'Ismi:'  Edit1.Text  #13 +

'Familiyasi:'  Edit2.Text  #13  'ro`yxatdan o`chirildi.',

mtInformation,[mbOk],0);

end

else  o`chirish so`ralgan tugun ro`yxatda yo`q

MessageDlg('Uzel'  #13  'Ismi:' Edit1.Text  #13 

'Familiyasi:' Edit2.Text #13  'ro`yxatda topilmadi.',

mtError,[mbOk],0);

Edit1.Text : '';

Edit1.SetFocus;

end;

Bu protsedura ro`yxatni to`la qarab chiqadi va ilova oynasi kiritish maydonida ko`rsatilgan tugunning bor yoki yo`qligini aniqlaydi. Agar mavjud bo`lsa, u holda foydalanuvchidan bu tugunni o`chirishga ijozat so`raydi. Agar foydalanuvchi OK tugmasi yordamida bu amalni tasdiqlasa, protsedura uni o`chiradi. Agar o`chiriladigan ma`lumot ro`yxatdan topilmasa, dastur bu haqida ekranga axborot chiqaradi.