.net - deleting rows from an excel file using c#

Question

I am opening an excel file like this:

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, "", false, false, 0, true, 1, 0);
xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);

I would like to know:
How do I loop through all the rows and delete every row in which the string SomeString does not appear in column A?

I know how to loop through every value:

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);
    }
}

But I do not know how to delete the entire row

Answer 1

Once you have a reference to the worksheet say

for(int i = 1; i <=100; i++)
{
  if(!worksheet.Cells[i,1].Contains("SomeString"))
  {
     ((Range)worksheet.Rows[i]).Delete(shiftDirection)
  }
}

where shiftDirection see here: Range.Delete method

You may have to cast the Cell's content to a string.