EASY WAY TO AVOID ADDING DUPLICATE ITEMS TO STRING LISTS

String lists (TStringList) are great -- easy to manage, used by many components such as memos, list boxes, combo boxes, etc., and full of features. Here's how to avoid adding duplicate items to string lists: 

var
  sl : TStringList;
begin
  sl := TStringList.Create;
  with sl do
  begin
    Sorted     := True;
    Duplicates := dupIgnore;

    //
    // add your items here
    // all the duplicate items
    // will be ignored
    //
    Add( edit1.text );
  end;

  //
  // now you can assign the
  // string list with unique
  // items to listbox1 (example)
  //
  listbox1.Items.Assign( sl );

  sl.Free;
end;

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