Listbox Duplicates

[Destruktion]

I have two listboxes and a generate button.

Listbox1 is where i generate and add new random numbers.

Listbox2 is the main list where items from Listbox1 are added - if Listbox2 already contains items that are generated in Listbox1 they are not added.

Now to the problem, If i click the generate button and Listbox2 already contains a number found in Listbox1, nothing happens (expected), so I have to keep clicking the generate button until a new number is found and added.

I need to add something like a repeat..until statement to make sure that whenever I click that button a number is added, once it runs out of numbers from Listbox1 to add show a message to say that no more can be added.

The problem is whenever I tried implementing the repeat statement, the Listbox1 went crazy looking for numbers that are not a duplicate in Listbox2 - of course it ran out of numbers and got stuck in a infinite loop.

Here is the code I came up with:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    Panel1: TPanel;
    Panel2: TPanel;
    Label1: TLabel;
    ListBox1: TListBox;
    Label2: TLabel;
    ListBox2: TListBox;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

function ListBoxItemExists(ListBox: TListBox; const Item: string): Boolean;
begin
  Result := ListBox.Items.IndexOf(Item) >= 0;
end;

procedure ShuffleStrings(sl : TStrings; nIntensity: integer);
var
  n1, n2, n3 : integer;
  s1         : string;
begin
  if(0 = nIntensity)then
  begin
    nIntensity := sl.Count;
  end else
  if(nIntensity > sl.Count)then
  begin
    nIntensity := sl.Count;
  end;

  Randomize;

  for n1 := 1 to nIntensity do
  begin
    n2 := Random( nIntensity );
    n3 := Random( nIntensity );

    s1             := sl.Strings[n3];
    sl.Strings[n3] := sl.Strings[n2];
    sl.Strings[n2] := s1;
  end;
end;

function ListBoxGenerateAndCompare(List, ListToCompare: TListBox; MinGen, MaxGen, MinRange, MaxRange: Integer; DoRandomize: Boolean): Boolean;
var
  SL: TStringList;
  i: Integer;
begin
  try
    SL:= TStringList.Create;
    try
      for i:= MinGen to MaxGen do
        SL.Add(IntToStr(i));

      if DoRandomize then ShuffleStrings(SL, 0);
      List.Items.Assign(SL);
    finally
      SL.Free;
    end;
  except on exception do
    //
  end;

  try
    SL:= TStringList.Create;
    try
      for i:= MinRange to MaxRange do
      begin
        if ListBoxItemExists(ListToCompare, List.Items.Strings[i]) then
        begin
          Result:= False
        end else
        begin
          if not ListBoxItemExists(ListToCompare, List.Items.Strings[i]) then
          begin
            SL.Add(List.Items.Strings[i]);
            ListToCompare.Items.AddStrings(SL);

            Result:= True;
          end;
        end;
      end;
    finally
      SL.Free;
    end;
  except on exception do
    //
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  Count: Integer;
begin
  Count:= ListBox2.Items.Count;

  // THIS SHOULD REPEAT UNTIL A NUMBER IS ADDED TO LISTBOX2,
  // IF there are no more numbers available show a message to say so

  ListBoxGenerateAndCompare(ListBox1, ListBox2, 1, 10, 0, 0, True);

  if ListBox2.Items.Count = Count + 1 then
    ShowMessage('New Number was added')
  else
    ShowMessage('No new number was added');
end;

end.

Appreciate some help thanks.

 

[Glenn9999]

Try this:

for i:= MinRange to MaxRange do
  begin
    if ListBoxItemExists(ListToCompare, List.Items.Strings[i]) > -1 then
      begin
        SL.Add(List.Items.Strings[i]);
        ListToCompare.Items.AddStrings(SL);
        Result:= True;
      end
    else
      Result := false;
  end;

It is not possible for anyone to acknowledge truth when their salary depends on them not doing it.

 

[Glenn9999]

No edit function...

This:

 if ListBoxItemExists(ListToCompare, List.Items.Strings[i]) > -1 then

Should be this:

if ListToCompare.Items.IndexOf(List.Items.Strings[i]) > -1 then

It is not possible for anyone to acknowledge truth when their salary depends on them not doing it.