C# Discussion Boards - CodeProject

19-Apr-16 4:19

Im very new to C# and am trying to use conversion tools to change some VB over. Im not quite sure how to remedy this error, so any help I can get is greatly appreciated!

This is the error Im receiving:

"CS0266: Cannot implicitly convert type 'System.Web.UI.Control' to 'System.Web.UI.WebControls.LinkButton'. An explicit conversion exists (are you missing a cast?)"

for Line 93

myDeleteButton = myTableCell.Controls[0];

Here is the full C# code:

public void Page_Load(object Source, EventArgs E)
{
	if (!Page.IsPostBack)
	{
		BindData();
	}
}

public void BindData()
{
	DataSet myDataSet = new DataSet();
	SqlDataAdapter mySqlDataAdapter = default(SqlDataAdapter);
	mySqlDataAdapter = new SqlDataAdapter("SELECT * FROM glmaster", "REMOVED;");
	mySqlDataAdapter.Fill(myDataSet, "glmaster");
	glmasterInfo.DataSource = myDataSet.Tables["glmaster"];
	glmasterInfo.DataBind();
}

public void DataGrid_Delete(object Source, DataGridCommandEventArgs E)
{
	SqlConnection myConnection = default(SqlConnection);
	SqlCommand myCommand = default(SqlCommand);
	string strDeleteStmt = "";
	
	decimal balance_test = new decimal();
	string Balance_output = "";
	
	balance_test = System.Convert.ToDecimal(Convert.ToDecimal(E.Item.Cells[6].Text));
	
	if (balance_test == 0.0M)
	{
		outError.InnerHtml = "";
		strDeleteStmt = "DELETE FROM glmaster " + 
			" WHERE major = " + E.Item.Cells[1].Text + 
			" AND minor = " + E.Item.Cells[2].Text + 
			" AND sub1 = " + E.Item.Cells[3].Text + 
			" AND sub2 = " + E.Item.Cells[4].Text;
		try
		{
			myConnection = new SqlConnection(
				"REMOVED;");
			myCommand = new SqlCommand(strDeleteStmt, myConnection);
			myConnection.Open();
			myCommand.ExecuteNonQuery();
			
			glmasterInfo.EditItemIndex = -1;
			BindData();
		}
		catch (Exception exc)
		{
			outError.InnerHtml = "* Error while deleting data.<br />" 
				+ exc.Message + "<br />" + exc.Source;
		}
		finally
		{
			myConnection.Close();
		}
	}
	else
	{
		Balance_output = balance_test.ToString("C");
		string Error_String = "";
		
		Error_String = "<center>You Can\'t Delete This Account<br>";
		Error_String = Error_String + "Balance is NOT zero.<br>";
		Error_String = Error_String + "The Account Balance is " + Balance_output;
		Error_String = Error_String + " for ";
		Error_String = Error_String + E.Item.Cells[1].Text + "-";
		Error_String = Error_String + E.Item.Cells[2].Text + "-";
		Error_String = Error_String + E.Item.Cells[3].Text + "-";
		Error_String = Error_String + E.Item.Cells[4].Text + "</center>";
		
		outError.InnerHtml = Error_String;
	}
}

public void DataGrid_ItemCreated(object Sender, DataGridItemEventArgs e)
{
	if (((e.Item.ItemType == ListItemType.Item) || (e.Item.ItemType == ListItemType.AlternatingItem)) || (e.Item.ItemType == ListItemType.EditItem))
	{
		TableCell myTableCell = default(TableCell);
		myTableCell = e.Item.Cells[0];

		LinkButton myDeleteButton = default(LinkButton);
		myDeleteButton = myTableCell.Controls[0];
		myDeleteButton.Attributes.Add("onclick", "javascript: return confirm(\'Are you Sure you want to delete this account?\');");
	}
}

modified 19-Apr-16 11:29am.

Richard MacCutchan19-Apr-16 5:09

Richard MacCutchan

19-Apr-16 5:09

It would really help us to help you if you actually indicated (with a comment) where the error occurs.

Collectoons19-Apr-16 5:16

19-Apr-16 5:16

sorry about that. Line 93

myDeleteButton = myTableCell.Controls[0];

Richard MacCutchan19-Apr-16 5:26

Richard MacCutchan

19-Apr-16 5:26

Please edit your original question and add the information there, so anyone else reading the question can see the details.

Richard Deeming19-Apr-16 5:56

Richard Deeming

19-Apr-16 5:56

Your code is vulnerable to SQL Injection[^]. NEVER use string concatenation to build a SQL query. ALWAYS use a parameterized query.

Everything you wanted to know about SQL injection (but were afraid to ask) | Troy Hunt[^]
How can I explain SQL injection without technical jargon? | Information Security Stack Exchange[^]
Query Parameterization Cheat Sheet | OWASP[^]

As to your question, you need to cast the control to the correct type. If you're certain that the control will always be of the correct type, then use:

myDeleteButton = (LinkButton)myTableCell.Controls[0];

If there's any chance that it might not be the correct type, then use:

myDeleteButton = myTableCell.Controls[0] as LinkButton;
if (myDeleteButton != null) { ... }

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Collectoons19-Apr-16 6:03

19-Apr-16 6:03

Your first suggestion worked perfectly! Thanks so much for your help

Richard Deeming19-Apr-16 6:06

Richard Deeming

19-Apr-16 6:06

Don't ignore the SQL Injection vulnerability - it's so simple to exploit, even a 3 year old can do it:
Hacking is child's play - SQL injection with Havij by 3 year old - YouTube[^]

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Collectoons19-Apr-16 6:08

Error Starting Windows Service

19-Apr-16 6:08

Ill be sure to work on it. Thanks

Member 1098552419-Apr-16 2:52

Member 10985524

19-Apr-16 2:52

I have created a windows File watcher Service which works fine on Development PC but when i am trying to install and start in other PC , it throws an error
Windows could not start the {name of service} service on Local Computer. Error 1067: The process terminated unexpectedly.

Please help

Re: Error Starting Windows Service

Eddy Vluggen19-Apr-16 2:57

Eddy Vluggen

19-Apr-16 2:57

Means there has been an exception that you did not handle, or that there was no work. Does the folder that you are watching exist? Does the service (that runs under different credentials than the user) have the correct rights to access that directory?

Open the services, locate yours, right-click and change the user under which it runs to your account.

Bastard Programmer from Hell Suspicious | :suss:

If you can't read my code, try converting it here[^]

Socket Example UWP

Miwin Solutions19-Apr-16 1:13

Miwin Solutions

19-Apr-16 1:13

I am new to UWP, so please forgive me!
I have been trying to implement a TCP Server \ Client, as outlined in the Microsoft example:

[^]
If I try this out on my local machine, it works fine (app generates server & client). If I then try on my remote machine (Minnowboard Turbot), I dont get a connection, or receive any data.
I have also tried (from both Local & Remote machine) connecting to a TCP Server program that I already have written. Whilst I get a connection to the server, I dont receive any data from the server (which is sending data every second).
Does anyone know what mistake I am making?
Thanks for any advice
Mike

Jochen Arndt19-Apr-16 2:18

Jochen Arndt

19-Apr-16 2:18

Such problems are usually sourced by firewalls filtering out the data packets.

You must configure the local Windows firewall for the system running the server process to accept incoming packets on the listening port.

If the systems are not in the same subnet (local network), it may be also necessary to allow the same packets on the firewall of the server side (e.g. a router).

Miwin Solutions20-Apr-16 2:16

Miwin Solutions

20-Apr-16 2:16

Hi Jochen, thanks for your help!
I have had a little more success. In the project capabilities, I just had Private Networks (Client & Server) ticked. I have now ticked Internet (Client & Server), and my test project is now able to send & receive data on both the local & remote machine (to itself (ie app is client & server)). If I create 2 projects - one server, one client and run one on the Local & one on the Remote, it can now connect, Send & Receive in either direction.
If I then try to connect my Client to my Original Server (written Visual studio C# 2010), I can connect from my Client and send data (from Client to Server). I DO NOT however receive any data from my Server to my client. This is the same for either the Local or Remote machines.
I have just fired up Wireshark, and this does see the Server Sent client.
My Client Code is this:

private async void CreateClient()
  {
      try
      {
          //Create the StreamSocket and establish a connection to the echo server.
          socket = new Windows.Networking.Sockets.StreamSocket();

          Windows.Networking.HostName serverHost = new Windows.Networking.HostName("192.168.1.19");//localhost");


          string serverPort = "7001";
          await socket.ConnectAsync(serverHost, serverPort);


          //Read data from the echo server.
          Stream streamIn = socket.InputStream.AsStreamForRead();
          streamIn.Flush();
          StreamReader reader = new StreamReader(streamIn);

          while (true)
          {
              //client receive
              string response = await reader.ReadLineAsync();
          }
      }
      catch (Exception e)
      {
          //Handle exception here.
      }
  }

Has anyone any suggestions?
Thanks
Mike

Jochen Arndt20-Apr-16 2:58

Jochen Arndt

20-Apr-16 2:58

This is difficult to answer with the available information.

You did not show the code that is sending to the server.

So I can just guess that you are doing that before creating the input stream and the reader. Then the data from the server may have been received already and are discarded by calling Flush().

I can only suggest to try it this way:

Stream streamIn = socket.InputStream.AsStreamForRead();
// Remove this (should be not necessary)
// streamIn.Flush();
StreamReader reader = new StreamReader(streamIn);

// Send data to the server here after the input stream has been created

while (true)
{
    //client receive
    string response = await reader.ReadLineAsync();
}

If this does not help you should debug the client code.

Miwin Solutions20-Apr-16 3:52

Miwin Solutions

20-Apr-16 3:52

Ah, I have got it working!
What I have done is added a '\r' (or '\n') to the end of the string of data being sent from my Server program (written in VS2010 C#). The data is now seen by the Client when the app is run on BOTH the Local & Remote Machine.
I dont need to '\r' character when sending FROM Client TO Server for the server to see the data.
Don't know why my program worked with VS2010 (client & server), but now has to be modded, to work with VS2015 Client. Guess as it now works, I am not too bothered!
Thanks for your time & help!
Mike