class Program
    {
        static void Main(string[] args)
        {
            // Revise this path to the location of a file that contains hidden worksheets.
            const string DEMOPATH = @"..\..\Documents\Sheets11.xlsx";
            List sheets = GetHiddenSheets(DEMOPATH);
            foreach (var sheet in sheets)
            {
                Console.WriteLine(sheet.Name);
            }
            Console.ReadLine();
        }
        public static List GetHiddenSheets(string fileName)
        {
            List returnVal = new List();

            using (SpreadsheetDocument document = SpreadsheetDocument.Open(fileName, false))
            {
                WorkbookPart wbPart = document.WorkbookPart;
                var sheets = wbPart.Workbook.Descendants();

                // Look for sheets where there is a State attribute defined, 
                // where the State has a value,
                // and where the value is either Hidden or VeryHidden.
                var hiddenSheets = sheets.Where((item) => item.State != null &&
                    item.State.HasValue &&
                    (item.State.Value == SheetStateValues.Hidden ||
                    item.State.Value == SheetStateValues.VeryHidden));

                returnVal = hiddenSheets.ToList();
            }
            return returnVal;
        }
    }

class Program
    {
        static void Main(string[] args)
        {
            const string DEMOPATH = @"..\..\Documents\Sheets11.xlsx";
            List sheets = GetHiddenSheets(DEMOPATH);
            foreach (var sheet in sheets)
            {
                Console.WriteLine(sheet.Name);
            }
            Console.ReadLine();
        }
        public static List GetHiddenSheets(string fileName)
        {
            List returnVal = new List();

            //Initialize a new Workboook object
            Workbook workbook = new Workbook();

            //Load the document
            workbook.LoadFromFile(fileName);

            //Judge whether a sheet is hidden
            foreach (Worksheet sheet in workbook.Worksheets)
            {
                if (sheet.Visibility == WorksheetVisibility.Hidden)
                {
                    returnVal.Add(sheet);
                }
            }
            return returnVal;
        }
    }

class Program
    {
        static void Main(string[] args)
        {
            var result = GetDefinedNames(@"..\..\Documents\Sheet10.xlsx");
            foreach (var dn in result)
                Console.WriteLine("{0} {1}", dn.Key, dn.Value);
            Console.ReadLine();
        }
        public static Dictionary GetDefinedNames(String fileName)
        {
            // Given a workbook name, return a dictionary of defined names.
            // The pairs include the range name and a string representing the range.
            var returnValue = new Dictionary();

            // Open the spreadsheet document for read-only access.
            using (SpreadsheetDocument document = SpreadsheetDocument.Open(fileName, false))
            {
                // Retrieve a reference to the workbook part.
                var wbPart = document.WorkbookPart;

                // Retrieve a reference to the defined names collection.
                DefinedNames definedNames = wbPart.Workbook.DefinedNames;

                // If there are defined names, add them to the dictionary.
                if (definedNames != null)
                {
                    foreach (DefinedName dn in definedNames)
                        returnValue.Add(dn.Name.Value, dn.Text);
                }
            }
            return returnValue;
        }
    }

class Program
    {
        static void Main(string[] args)
        {
            string strDoc = @"..\..\Documents\Sheet10.xlsx";
            Dictionary result = GetDefinedNames(strDoc);
            foreach (var dn in result)
                Console.WriteLine("{0} {1}", dn.Key, dn.Value);
            Console.ReadLine();
        }
        public static Dictionary GetDefinedNames(String fileName)
        {

            var returnValue = new Dictionary();

            //Initialize a new Workboook object
            Workbook workbook = new Workbook();

            //Load the document
            workbook.LoadFromFile(fileName);

            //Getting all named ranges
            INameRanges range = workbook.NameRanges;

            //If there are items in Ranges, add them to the dictionary.
            if (range != null)
            {
                foreach (INamedRange rn in range)
                    returnValue.Add(rn.Name, rn.Value.ToString());
            }
            return returnValue;
        }
    }

class Program
    {
        static void Main(string[] args)
        {
            string strDoc = @"..\..\Documents\Sheet9.xlsx";
            Stream stream = File.Open(strDoc, FileMode.Open);
            OpenAndAddToSpreadsheetStream(stream);
            stream.Close();
        }
        public static void OpenAndAddToSpreadsheetStream(Stream stream)
        {
            // Open a SpreadsheetDocument based on a stream.
            SpreadsheetDocument spreadsheetDocument =SpreadsheetDocument.Open(stream, true);

            // Add a new worksheet.
            WorksheetPart newWorksheetPart = spreadsheetDocument.WorkbookPart.AddNewPart();
            newWorksheetPart.Worksheet = new Worksheet(new SheetData());
            newWorksheetPart.Worksheet.Save();

            Sheets sheets = spreadsheetDocument.WorkbookPart.Workbook.GetFirstChild();
            string relationshipId = spreadsheetDocument.WorkbookPart.GetIdOfPart(newWorksheetPart);

            // Get a unique ID for the new worksheet.
            uint sheetId = 1;
            if (sheets.Elements().Count() > 0)
            {
                sheetId = sheets.Elements().Select(s => s.SheetId.Value).Max() + 1;
            }

            // Give the new worksheet a name.
            string sheetName = "Sheet" + sheetId;

            // Append the new worksheet and associate it with the workbook.
            Sheet sheet = new Sheet() { Id = relationshipId, SheetId = sheetId, Name = sheetName };
            sheets.Append(sheet);
            spreadsheetDocument.WorkbookPart.Workbook.Save();

            // Close the document handle.
            spreadsheetDocument.Close();

            // Caller must close the stream.
        }
    }

class Program
    {
        static void Main(string[] args)
        {
            string strDoc = @"..\..\Documents\Sheet9.xlsx";
            Stream stream = File.Open(strDoc, FileMode.Open);
            OpenAndAddToSpreadsheetStream(stream);
            stream.Close();
        }
        public static void OpenAndAddToSpreadsheetStream(Stream stream)
        {
            //Initialize a new Workboook object
            Workbook workbook = new Workbook();

            //Load workbook from stream
            workbook.LoadFromStream(stream);

            //Append a new sheet to worksheet and then name it
            int count = workbook.Worksheets.Count + 1;
            workbook.Worksheets.Create("Sheet" + count);

            //Save workbook to disk
            workbook.Save();
        }
    }