[Страдалецъ]

Вот ведь. Ну вот вам рабочий пример:

Код:

program Project37;

{$APPTYPE CONSOLE}
Const
  ArrSize = 20;

Var
  A: Array of Integer;
  i,Val: Integer;
  NewSearch: Boolean;
begin
 Randomize;
 SetLength(A, 0);
 while Length(A) < ArrSize
 do begin
    Val := Random(ArrSize);
    NewSearch := False;
    for i := 0 to High(A)
    do if A[i] = Val
       then begin
            NewSearch := True;
            Break;
            end;
    if NewSearch then Continue;
    SetLength(A,Length(A)+1);
    A[High(A)] := Val;
    end;
  for i := 0 to High(A)
  do WriteLn(A[i]);
  ReadLn;
end.