Microsoft.Office.Interop.Excel Find 操作

public void SearchLoactions(string filepath, int start, int end ,string expectvalue)
{
if (end >= start)
{
Application xlApp = new Application();
try
{
if (!File.Exists(filepath))
throw new FileNotFoundException("Can not find the file, please check whether the file exists");
var xlWorkBook = xlApp.Workbooks.Open(filepath, 0, true, 5, "", "", true, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0);

//code that fails or just returns bad ansvers:
//This code just returns a list of worksheets
//var worksheetlist = xlWorkBook.Worksheets.Cast().ToList();

var sheet = (Worksheet)xlApp.ActiveWorkbook.Worksheets[2];
var rgUsed = sheet.get_Range("S7:BZ105");
var rgFound = sheet.Range["S7", "BZ105"].Cells.Find(expectvalue, Type.Missing, XlFindLookIn.xlValues, XlLookAt.xlPart, XlSearchOrder.xlByRows, XlSearchDirection.xlNext, Type.Missing, Type.Missing, Type.Missing);
Range rgTmp = rgFound;
do
{
var item = rgTmp.get_Value();
Console.WriteLine("Value:" + item);
int iRowNum = rgTmp.Row;
Console.WriteLine("Row:"+iRowNum);
int iColNum = rgTmp.Column;
Console.WriteLine("Column:"+iColNum);
rgTmp = rgUsed.FindNext(rgTmp);
Console.WriteLine("---------------------------");
} while (rgTmp.Address != rgFound.Address);//记录第一个找到的range地址，当下一个单元格的地址与第一个相同，则跳出。

}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
Debug.WriteLine(ex.Message);
}
finally
{
xlApp.Quit();
System.Runtime.InteropServices.Marshal.ReleaseComObject(xlApp);
xlApp = null;
}

//return itemlst;
}
else
{
//return null;
}
}