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Question

我正在尝试将excel转换为dataset进行某些处理。我使用以下代码：

private DataSet ConvertExcelToDataset(string path, string sheetName)
{
    Excel.Application oExcel = null;
    Excel.Workbooks workbooks = null;
    Excel.Workbook workbook = null;
    Excel.Range range = null;

    try
    {
        oExcel = new Excel.Application();
        workbooks = oExcel.Workbooks;
        workbook = workbooks.Open(path);

        DataSet ds = new DataSet();

        foreach (Excel.Worksheet sheet in workbook.Worksheets)
        {
            //If passed sheetName is "All" then reading all sheets
            //If passed sheetName is not "All" then reading only sheet whose name is passed
            if (sheetName != "All" && sheet.Name != sheetName)
            {
                continue;
            }

            range = sheet.UsedRange;

            int rows = range.Rows.Count;
            int cols = range.Columns.Count;
            DataTable dt = new DataTable(sheet.Name);
            int noofrow = 1;

            //If 1st Row Contains unique Headers for datatable include this part else remove it                    
            for (int c = 1; c <= cols; c++)
            {
                string colname = sheet.Cells[1, c].Text;
                dt.Columns.Add(colname);
                noofrow = 2;
            }

            for (int r = noofrow; r <= rows; r++)
            {
                DataRow dr = dt.NewRow();

                for (int c = 1; c <= cols; c++)
                {
                    dr[c - 1] = sheet.Cells[r, c].Text;
                }
                dt.Rows.Add(dr);
            }

            ds.Tables.Add(dt);

            //clean up  
            Marshal.ReleaseComObject(sheet);
        }

        //Closing workbook
        workbook.Close();
        //Closing excel application
        oExcel.Quit();

        return ds;
    }
    catch (Exception ex)
    {
        _logger.Error(ex);

        return null;
    }
    finally
    {
        //clean up           
        if (range != null) Marshal.ReleaseComObject(range);
        if (workbook != null) Marshal.ReleaseComObject(workbook);
        if (workbooks != null) Marshal.ReleaseComObject(workbooks);
        if (oExcel != null) Marshal.ReleaseComObject(oExcel);
    }
}

它工作正常但是如果假设excel文件中的行中的任何单元格包含包含超过30,000个字符的大字符串，则会被截断。经过调试后，我发现了以下行中的问题

dr[c - 1] = sheet.Cells[r, c].Text;

那么我怎样才能避免这种字符串截断？