public static string XlsToXlsx(string excelFile)
{
if (excelFile == null)
{
throw new FileNotFoundException("Nie znaleziono pliku");
}
if (excelFile.ToLower()[excelFile.Length - 1] == 'x')
{
throw new Exception("Niepoprawny typ pliku, oczekiwano .xls");
}
var xlsFileName = new FileInfo(excelFile);
var savePath = xlsFileName.FullName.Remove(xlsFileName.FullName.Length - 4);
var xlsFile = new Application().Workbooks;
var workbook = xlsFile.Open(excelFile);
workbook.SaveAs(savePath + ".xlsx", XlFileFormat.xlOpenXMLWorkbook);
workbook.Close(false);
xlsFile.Close();
File.Delete(xlsFileName.FullName);
return(excelFile + 'x');
}
