Mirsaid Aripov, Nurillo Otaxanov

if list[i] <> NIL

then st : st  list[i].Info  #13;

ShowMessage (st);

Massivning har bir elementi Tstud tipidagi ob’yektlarni ham, Tprof tipidagi ob’yektlarni ham olishi mumkin. Polimorfizm konsepsiyasi aynan har bir ob’yektning tipiga mos bo`lgan metodni qo`llashni ta`minlaydi.

Quyidagi dastur TPerson, TStud va Tprof klasslari yordamida talaba va o`qituvchilar ro`yxatini hosil qiladi va ekranga chiqaradi (10.1-listing, 10.1-rasm).



10.1-rasm. Polimorfizm dasturining dialog oynasi

10.1-listing. Polimorfizm

type

 bazaviy klass

TPerson  class

fName: string;  nom

constructor Create(name:string);

function info:string;

virtual;

end;

 Talaba klassi

TStud  class(TPerson)

fGr : integer;  guruh nomeri

constructor Create(name:string;gr:integer);

function info:string;

override;

end;

 O`qituvchi klassi

TProf  class(TPerson)

fdep:string;  kafedra nomi

constructor Create(name:string;dep:string);

function info:string; override;

end;

const SZL  10;  ro`yxat xajmi

var

Form1: TForm1;

List: array[1..SZL] of TPerson;  ro`yxat

n:integer  0;  ro`yxatdagi odamlar soni

implementation

{$R *.DFM}

constructor TPerson.Create(name:string);

begin

fName : name;

end;

constructor TStud.Create(name:string;gr:integer);

begin

inherited create(name);  bazaviy klass konstruktorini chaqirish

fGr : gr;

end;

constructor TProf.create(name:string; dep:string);

begin

inherited create(name);  bazaviy klass konstruktorini chaqirish

fDep : dep;

end;

function TPerson.Info:string;

begin

result : fname;

end;

function TStud.Info:string;

begin

result : fname  ' gr.'  IntToStr(fGr);

end;

function TProf.Info:string;

begin

result : fname  ' kaf.'  fDep;

end;

 Qo`shib qo`yish tugmasi chertilganda

procedure TForm1.Button1Click(Sender: TObject);

begin

if n < SZL then

begin  ob’yektn ro`yxatga qo`shish

N : n  1;

if Radiobutton1.Checked

then  TStud ob’yektini yaratiladi

List[n] : TStud.Create(Edit1.Text,StrToInt(Edit2.Text))

else  TProf ob’yektini yaratiladi

List[n] : TProf.Create(Edit1.Text,Edit2.Text);

 kiritish maydoni tozalanadi

Edit1.Text : '';

Edit2.Text : '';

Edit1.SetFocus;  kursor Familiya maydoniga o`tkaziladi

end

else ShowMessage('ro`yxat to`ldi!');

end;

procedure TForm1.Button2Click(Sender: TObject);

var

i:integer;  indeks

st:string;  ro`yxat

begin

for i : 1 to SZL do

if list[i] <> NIL then st : st  list[i].info  #13;

ShowMessage('ro`yxat'  #13  st);

end;

end.

Tform1.Button1Click protsedurasi (Qo`shib qo`yish) Tsud yoki Tprof klassidagi list[n] ob’yektini hosil qiladi. Yaratilayotgan ob’yektning klassi RadioButton o`chirgichlari holati bilan aniqlanadi. O`chirgich Talaba (RadioButton1) holatida bo`lsa Tstud klassi, O`qituvchi (RadioButton2) da esa Tprof klassini aniqlanadi.

TForm1.Button2Slick protsedurasi (Ro`yxat) ro`yxatning har bir elementiga info metodini qo`llaydi hamda umumiy ro`yxatdan iborat bo`lgan satrni hosil qiladi.