How convert datatable to string in c#

public static string ConvertDataTableToString(this DataTable dt) {     StringBuilder JsonString = new StringBuilder();     //Exception Handling            if (dt != null && dt.Rows.Count > 0)     {         JsonString.Append("{ ");         JsonString.Append("\"Head\":[ ");         for (int i = 0; i < dt.Rows.Count; i++)         {             JsonString.Append("{ ");             for (int j = 0; j < dt.Columns.Count; j++)             {                 if (j < dt.Columns.Count - 1)                 {                     JsonString.Append("\"" +                       dt.Columns[j].ColumnName.ToString().Trim() + "\":" +                       "\"" + dt.Rows[i][j].ToString().Trim() + "\",");                 }                 else if (j == dt.Columns.Count - 1)                 {                     //string cleaned = original.Replace(@"\""", "");                     JsonString.Append("\"" +                       dt.Columns[j].ColumnName.ToString().Trim() +                       "\":" + "\"" +                       dt.Rows[i][j].ToString().Trim().CleanInput() + "\"");                 }             }             /*end Of String*/             if (i == dt.Rows.Count - 1)             {                 JsonString.Append("} ");             }             else             {                 JsonString.Append("}, ");             }         }         JsonString.Append("]}");         return JsonString.ToString();     }     else     {         return null;     } }

                                         

private static String CleanInput(this string strIn)         {             // Replace invalid characters with empty strings.             return Regex.Replace(strIn, @"[^\w\.@-]", " ");         }