How to generate PDF version of Crystal Reports programmatically?

ReportDocument O_Report=new ReportDocument();
ExportOptions exportOpts =newExportOptions();
PdfRtfWordFormatOptions pdfFormatOpts =newPdfRtfWordFormatOptions ();
DiskFileDestinationOptions diskOpts =newDiskFileDestinationOptions();

exportOpts = O_Report.ExportOptions;//Set the PDF format options.exportOpts.ExportFormatType = ExportFormatType.PortableDocFormat;
exportOpts.FormatOptions = pdfFormatOpts;//Set the disk file options and export.exportOpts.ExportDestinationType = ExportDestinationType.DiskFile;
diskOpts.DiskFileName ="C://Trial.pdf";//This is the path where the file will be savedexportOpts.DestinationOptions = diskOpts;

O_Report.Export ();