C# - Excel save as *.xlsx format (Excel 2007 format)

C#에서 xls를 xlsx로 저장하면 읽을수 없다. 물론 확장자를 xls로 변경하면 읽어지긴 하는데 불편

Excel 2007 format 으로 저장

저장방법

http://stackoverflow.com/questions/9769703/exporting-to-xlsx-using-microsoft-office-interop-excel-saveas-error

This is how you save the relevant file as a Excel12 (.xlsx) file... It is not as you would intuitively think i.e. using Excel.XlFileFormat.xlExcel12 but Excel.XlFileFormat.xlOpenXMLWorkbook. The actual C# command was

excelWorkbook.SaveAs(strFullFilePathNoExt, Excel.XlFileFormat.xlOpenXMLWorkbook, Missing.Value,
    Missing.Value, false, false, Excel.XlSaveAsAccessMode.xlNoChange, 
    Excel.XlSaveConflictResolution.xlUserResolution, true, 
    Missing.Value, Missing.Value, Missing.Value);

I hope this helps someone else in the future.