protected void Button1_Click(object sender, EventArgs e) { SautinSoft.PdfMetamorphosis p = new SautinSoft.PdfMetamorphosis(); //After purchasing the license, please insert your serial number here to activate the component //p.Serial = "XXXXXXXXXXX"; ArrayList pdfs = new ArrayList(); int files = 0; if (FileUpload1.FileBytes.Length > 0) { pdfs.Add(FileUpload1.FileBytes); files++; } if (FileUpload2.FileBytes.Length > 0) { pdfs.Add(FileUpload2.FileBytes); files++; } if (FileUpload3.FileBytes.Length > 0) { pdfs.Add(FileUpload3.FileBytes); files++; } if (files < 2) { Result.Text = "Error! Before merging please select at least two PDF documents!"; return; } byte[] pdfBytes = null; //merge pdfBytes = p.MergePDFStreamArrayToPDFStream(pdfs); //show PDF if (pdfBytes != null) { Response.Buffer = true; Response.Clear(); Response.ContentType = "application/PDF"; Response.AppendHeader("content-disposition", "attachment; filename=single.pdf"); Response.BinaryWrite(pdfBytes); Response.Flush(); Response.End(); } else { Result.Text = "Error in merging these PDF files, email to [email protected]!"; } }