我如何在C＃中转换具有多种类型的字符串

Question

I am getting a cast error for the Url value. Does anyone know how to cast a value to a string that contains multiple value types?

CmdRecipients = new OleDbCommand(QueryRecipients, ConnRecipients);
Recipients = CmdRecipients.ExecuteReader();

while (Recipients.Read())
{
    Url = "https://bulktext.vodafone.ie/sendmessage.aspx"
          + "?user=user&password=user1!&api_id=89&to="
          + Recipients.GetString(8)
          + "&text=" + Confirmations.GetString(4)
          + "%0d%0a" + Confirmations.GetString(5)
          + "%0d%0a" + Confirmations.GetString(6)
          + "&from=Service";

    Console.Write("Sending text to " + Recipients.GetString(8) + " ... ");

    //Send SMS Here
    HttpWebRequest req = WebRequest.Create(Url) as HttpWebRequest;
    string result = null;
    using (HttpWebResponse resp = req.GetResponse() as HttpWebResponse)
    {
        StreamReader reader = new StreamReader(resp.GetResponseStream());
        result = reader.ReadToEnd();
        if (result == "0\nRequest deferred successfully")
        {
            QueryRecipients = "UPDATE [Test].[dbo].[MessagesToSend] SET Previous_Status = Current_Status,"
                              + "Current_Status = \"Sent\", DateTime_sent = Now() "
                              + "WHERE Task_ID = \"" + Recipients.GetString(2) + "\";";

            OleDbCommand Update = new OleDbCommand(QueryRecipients, ConnConfirmations);
            Update.ExecuteNonQuery();

            Console.WriteLine("Done!");
        }
        else
        {
            Console.WriteLine("The text wasn't delivered properly.");
        }
    }
}

Answer 1

Your question is a bit vague as you're not telling us where the exception is thrown, nor what the exception is exactly.

I would suspect that the problem lies in your use of Confirmations.GetString(x) and Recipients.GetString(x) . As I understand, these are results from database calls. If the respective fields returned by the select don't contain strings, the GetString call will fail. You need to use the method that matches the field's type, like GetBoolean , GetInt32 , etc.