unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ComCtrls, Vcl.ToolWin, Winapi.ShlObj, Winapi.ActiveX,
  System.IOUtils;

type
 TMyStrings = array of string;
  TForm1 = class(TForm)
    ToolBar1: TToolBar;
    SelectpathButton: TButton;

    procedure Button1Click(Sender: TObject);
    procedure SelectpathButtonClick(Sender: TObject);
    function  GetTextFiles(path:String):TStringList;
  private
    { Private declarations }
  public

    { Public declarations }
  end;

var

  Form1: TForm1;


implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
  I: Integer;
begin


end;
function TForm1.GetTextFiles(path: string):TStringList;
  var
    I:Integer;

    Temp_array:TArray<System.string>;

  begin

   Result:=TStringList.Create;
   Temp_array:= TDirectory.GetFiles(path);
   for i:=1 to Length( Temp_array) do
    begin
          if ExtractFileExt(Temp_array[i])='txt' then
             Result.Add(Temp_array[i]);
    end;
  end;


  function AdvSelectDirectory(const Caption: string;
    const Root: WideString; var Directory: string; EditBox: Boolean = False;
    ShowFiles: Boolean = False; AllowCreateDirs: Boolean = True): Boolean;

  function SelectDirCB(Wnd: HWND; uMsg: UINT; lParam, lpData: lParam)
    : Integer; stdcall;
  begin
    case uMsg of
      BFFM_INITIALIZED:
        SendMessage(Wnd, BFFM_SETSELECTION, Ord(True), Integer(lpData));
    end;
    Result := 0;
  end;

var
  WindowList: Pointer;
  BrowseInfo: TBrowseInfo;
  Buffer: PChar;
  RootItemIDList, ItemIDList: PItemIDList;
  ShellMalloc: IMalloc;
  IDesktopFolder: IShellFolder;
  Eaten, Flags: LongWord;
const
  BIF_USENEWUI = $0040;
  BIF_NOCREATEDIRS = $0200;
begin
  Result := False;
  if not DirectoryExists(Directory) then
    Directory := '';
  FillChar(BrowseInfo, SizeOf(BrowseInfo), 0);
  if (ShGetMalloc(ShellMalloc) = S_OK) and (ShellMalloc <> nil) then
  begin
    Buffer := ShellMalloc.Alloc(MAX_PATH);
    try
      RootItemIDList := nil;
      if Root <> '' then
      begin
        SHGetDesktopFolder(IDesktopFolder);
        IDesktopFolder.ParseDisplayName(Application.Handle, nil, POleStr(Root),
          Eaten, RootItemIDList, Flags);
      end;
      OleInitialize(nil);
      with BrowseInfo do
      begin
        hwndOwner := Application.Handle;
        pidlRoot := RootItemIDList;
        pszDisplayName := Buffer;
        lpszTitle := PChar(Caption);
        ulFlags := BIF_RETURNONLYFSDIRS or BIF_USENEWUI or BIF_EDITBOX *
          Ord(EditBox) or BIF_BROWSEINCLUDEFILES * Ord(ShowFiles) or
          BIF_NOCREATEDIRS * Ord(not AllowCreateDirs);
        lpfn := @SelectDirCB;
        if Directory <> '' then
          lParam := Integer(PChar(Directory));
      end;
      WindowList := DisableTaskWindows(0);
      try
        ItemIDList := ShBrowseForFolder(BrowseInfo);
      finally
        EnableTaskWindows(WindowList);
      end;
      Result := ItemIDList <> nil;
      if Result then
      begin
        ShGetPathFromIDList(ItemIDList, Buffer);
        ShellMalloc.Free(ItemIDList);
        Directory := Buffer;
      end;
    finally
      ShellMalloc.Free(Buffer);
    end;
  end;
end;



procedure TForm1.SelectpathButtonClick(Sender: TObject);
 var
  path,Root:String;
  fileList:TStringList;
begin
  fileList:=TStringList.Create;
  path:='c:\\';
 if AdvSelectDirectory('Выбор папки','',path)=true then
  begin
    fileList:= GetTextFiles(path);
    fileList.Free;
  end;
end;

end.