Excel and C# . net

Excel.Application xlApp ;
Excel.Workbook xlWorkBook ;
Excel.Worksheet xlWorkSheet ;
Excel.Range range ;

string str;
int rCnt = 0;
int cCnt = 0;

xlApp = new Excel.ApplicationClass();
xlWorkBook = xlApp.Workbooks.Open("csharp.net-informations.xls", 0, true, 5, "", "", true, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0);
xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);

range = xlWorkSheet.UsedRange;

for (rCnt = 1; rCnt <= range.Rows.Count; rCnt++)
{
for (cCnt = 1; cCnt <= range.Columns.Count; cCnt++)
{
str = (string)(range.Cells[rCnt, cCnt] as Excel.Range).Value2 ;
MessageBox.Show(str);
}
}

xlWorkBook.Close(true, null, null);
xlApp.Quit();