how i can get the sheet in excel by number in c# and how to close Excel applicatin after open it

Question

    var excelApp = new Excel.Application();
    var excelWorkbook = excelApp.Workbooks.Open(Program.FileName);
    var excelSheets1 = excelWorkbook.Worksheets;
    var excelWorksheet1 = (Excel.Worksheet)excelSheets1.Item["Sheet1"];
    for (var i = 2; i <= 62; i++)
    {

        for (var j = 2; j <= 5; j++)
        {
            var iRow = _dtCode1.NewRow();
            var cellValue = Convert.ToString(((Excel.Range)excelWorksheet1.Cells[i, j]).Value);
            var codeValue = Convert.ToString(((Excel.Range)excelWorksheet1.Cells[i + 1, j]).Value);
            iRow[0] = cellValue; iRow[1] = codeValue;
            _dtCode1.Rows.Add(iRow);
        }
        i = i + 1;
    }

this code above in

var excelWorksheet1 = (Excel.Worksheet)excelSheets1.Item["Sheet1"];

i wanna change Sheet1 by ID like the number of sheet in the woorkbook the second thing is there any way to close the excel file after open it

var excelWorkbook = excelApp.Workbooks.Open(Program.FileName);

Answer 1

To select a sheet using its index use:

Excel.Worksheet xlWorkSheetFocus = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);
xlWorkSheetFocus.Activate();

To close the workbook use

excelWorkbook.Close(); 

To quit Excel app:

excelApp.Quit();