mechanism to read an excel file >255 columns in c#

{
    //...
    string file_path = @"D:\doc\excel.xlsx";
    Microsoft.Office.Interop.Excel.Application xlApp =
        new Microsoft.Office.Interop.Excel.ApplicationClass();
    // Disabling messageboxes to prevent losing control on Excel app
    xlApp.DisplayAlerts = false;
    Microsoft.Office.Interop.Excel.Workbook xlWorkBook = 
        xlApp.Workbooks.Open(file_path, 0, false, 5, "", "", true, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0);
    xlWorkBook.DoNotPromptForConvert = true;
    for (int k = 1; k <= xlWorkBook.Worksheets.Count; k++){
        Microsoft.Office.Interop.Excel.Worksheet xlWorkSheet = (Microsoft.Office.Interop.Excel.Worksheet)this.xlWorkBook.Worksheets.get_Item(k);
        int cCnt = xlWorkSheet.Cells.Count;
        // processing all cells used, but can call named ranges
        Microsoft.Office.Interop.Excel.Range range = xlWorkSheet.UsedRange;
        for (int rCnt = 1; rCnt <= range.Rows.Count; rCnt++){
            for (cCnt = 1; cCnt <= range.Columns.Count; cCnt++){
                Microsoft.Office.Interop.Excel.Range rng =    (Microsoft.Office.Interop.Excel.Range)range.Cells[rCnt, cCnt];
                // do something with range
            }
        }
     }
    //...
}