C#

Path.GetInvalidFileNameChars

IndexOf

bool IsValidFilename(String ^fileName)
{
  if ( String::IsNullOrEmpty( fileName ) == true )
    return false;
  
  array<Char>^ invalidFileChar = System::IO::Path::GetInvalidFileNameChars();

  for each ( Char ^i in invalidFileChar )
  {
    if ( fileName->Contains(String::Format("{0}", i)) )
    {
      String ^tmp = String::Format(L" '{0}'  is invalid in a file name.\n", i);
      System::Windows::Forms::MessageBox::Show(gcnew String(tmp),gcnew String(L"Warning"), 
        MessageBoxButtons::OK);
      return false;
    }
  }

  return true;
}

protected override void OnPaint( PaintEventArgs e ) {
    base.OnPaint( e );

    if( ( this.Width <= 0 ) || ( this.Height <= 0 ) ) return;

    e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;

    GraphicsPath path = createGraphicPath( Shapes.Pie);

    this.Region = new Region( path );

    Pen pen = new Pen( new SolidBrush( borderColor_ ), borderWidth_ );
    pen.DashStyle = borderStyle_;

    e.Graphics.DrawPath( pen, path );

    path.Dispose();
    pen.Dispose();
}