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I need to create a list of type Dataset. Here is my code at the moment
List<<DataSet>> dsList = new List<<DataSet>>();
dsList.Add(payClass.GetPayItems());
How would I bind that list to a ListBox?
P.S - I added to << and >> because when posting it removes it.
Illegal Operation
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A ListBox can hold and show all kinds of items; by default, it calls ToString() on each of its items to visualize them.
There is an alternative by turning the ListBox into "OwnerDrawn" mode, which means you set out to provide all the code required to paint one item, see the DrawItem event.
If you were to bind a List<DataSet> to a ListBox, it would turn each DataSet into a single item in its collection; unless your DataSet has overridden its ToString() method, the net result would be something similar to the string "System.Data.DataSet" which I guess is not what you want. And painting a DataSet yourself would be a challenge.
So I think you are tackling this the wrong way. I'm not so sure what it is you really want to achieve.
PS: you can get proper < > & signs by using the little widgets above the editor box.
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Luc,
I have dataset that contains Items from my database. What I want to do is list all those payitems in listbox1 and then enable to user to add selecteditems to listbox2.
Illegal Operation
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Well, AFAIK a DataSet can only contain DataTables; so maybe you have one or several DataTables that hold DataRows with such payitem information. The easy way of presenting one DataTable to a user is by using a DataGridView (assuming you are talking about a WinForms application).
While I'm not an expert on DataTables and the like, I recently published my CP Vanity[^] article that uses both DataTable and DataGridView. I would suggest you read the MSDN documentation on the relevant classes, and have a look at my app. Assuming it looks like what you have in mind.
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string result = "";
append("Ali","Salim",&result);
public void append(string a, string b, string result)
{
result = a +" "+ b;
}
Error:
Error 11 Argument '4': cannot convert from 'string*' to 'string' D:\app\pup\Code\TBrectangular.aspx.cs 23 262 D:\app\
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It's telling you that result and &result are not the same thing. However, your public void append(string a, string b, string result) wouldn't do much anyway, since you can't modify function parameters without explicitly specifying.
CQ de W5ALT
Walt Fair, Jr., P. E.
Comport Computing
Specializing in Technical Engineering Software
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this is the C# forum, your code does not compile here.
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While in c++ that would work just fine, C# doesn't let you manage pointers or references directly without declaring a block of code unsafe (it might be worth it for you to look up the unsafe keyword and how to use it)
What C# does give you for just this type of thing is another couple of keywords for your parameters, ref and out. Both will allow you to pass the reference to your string so that you can modify it inside the function, but there is one main difference.
Using the out keyword you can pass in an uninitialised variable that you expect the function to fill in. The ref keyword will only allow you to pass in variables that have been initialised as it expects the function to use and modify it.
So, for this type of thing you can simply use the out keyword;
string result;
append("Ali", "Salim", result);
public void append(string a, string b, out string result)
{
result = a +" "+ b;
}
Now, on a slightly different topic, if you plan on combining a lot of strings you may simply want to use the StringBuilder class, as it is a lot more efficient than simply adding two or more strings together.
My current favourite word is: Smooth!
-SK Genius
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Or why not simply return the string like a normal person?
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Now you surprise me. 
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hey,
i'm listening to key_down event,
when it's fired, the following code are executed
private void typingTextBox_KeyDown(object sender, KeyEventArgs e)
{
char key = (char)e.KeyValue;
if (!e.Shift)
key = Char.Parse(key.ToString().ToLower());
wg.checkClickedKey(key);
}
but the problem is, that code is executed twice...
how it can be fixed ?
thanks
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my guess is that you've add an extra handler somewhere. Check your code and see how many
myTextBox.KeyDown += typingTextBox_KeyDown
statements there are. Remember there might be one in the designer code.
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absolutely right...
somehow it was generated twice in designer code....
thanks
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Btw, how about char.ToLower?
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right, much simpler
thanks
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FYI: the KeyDown/KeyUp events don't, but the KeyPress event offers a KeyPressEventArgs.KeyChar holding the character in its correct casing for free... however it only fires for keys that contribute to document content, not modifier keys such as shift, control, alt, ...
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so how this casing can help me ?
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I suggest you read the documentation, and try it.
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after msdn review, the KeyPress event doesn't help me, cause i don't need to filter the input
thanks anyway
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...here is the relevant code code:
private static void WriteArchive(string document, MessageType outboundInfo, string filePath, FtpWebRequest request)
{
try
{
using (MemoryStream memoryStream = new MemoryStream(document.Length))
{
int bufferSize = document.Length;
byte[] buffer = new byte[bufferSize];
UnicodeEncoding encoding = new UnicodeEncoding();
byte[] _document = encoding.GetBytes(document);
memoryStream.Write(_document, 0, _document.Length);
memoryStream.Seek(0, SeekOrigin.Begin);
request.Method = WebRequestMethods.Ftp.UploadFile;
request.UsePassive = true;
request.UseBinary = false;
request.KeepAlive = false;
using (Stream stream = request.GetRequestStream())
{
int content = memoryStream.Read(buffer, 0, bufferSize);
while (content != 0)
{
stream.Write(buffer, 0, content);
content = memoryStream.Read(buffer, 0, bufferSize);
}
}
}
}
catch (Exception ex)
{
throw ex;
}
}
When I stepped through, there were 2 executions of the loop. I was kind of puzzled by it, because I had set the buffersize to accept the whole enchilada. So, I stepped through again, and on memoryStream.Read, every other byte inside buffer is '0' . ...After the file was written, I opened it up in Notepad++ and confirmed that NULLS were being inserted into the file. Did I just do something stupid? Anyone know how to cull those NULL characters?
"I need build Skynet. Plz send code"
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Yup!! It was stupid alright. I had to paste my code in here before I even noticed it....I configured UnicodeEncoding when I obviously need my encoding to be ASCIIEncoding()
I'll leave this here so google searches might find it - remember that you need ASCIIEncoding if you're trying to upload an xml file lol
"I need build Skynet. Plz send code"
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I am trying to figure out how I can properly support multiple (& identical) events using a single delegate/handler. What I am experiencing is that I can easily tied my events to a single handler (i.e., using += ), but when any one of the events fire each instance of the handler method executes. I did not expect this behaviour as I had assumed that each delegate creation was instantiating a specific copy of itself and would be internally resolved. I have a full project space that shows this behaviour. Here is some code from the main program that shows the overall structure that I currently have:
namespace EventsDelegateIssue
{
public partial class MainForm : Form
{
#region - Variables -
DoSomeWork[] oDoSomeWork;
delegate void SetMessageCallback(string Message);
#endregion
#region - Constructor/Destructor -
public MainForm()
{
InitializeComponent();
//Create some worker objects and connect their events to handlers
oDoSomeWork = new DoSomeWork[3];
for (int i = 0; i < oDoSomeWork.Length; i++)
{
oDoSomeWork[i] = new DoSomeWork();
oDoSomeWork[i].Index = i;
oDoSomeWork[i].OnMessage += new PostMessageEvent.OnMessageEvent(MainForm_OnMessage);
onMessage_event += new onMessage_delegate(onMessage_method);
oDoSomeWork[i].OnData += new RaiseDataEvent.OnRaiseDataEvent(MainForm_OnData);
onData_event += new onData_delegate(onData_method);
}
}
#endregion
#region - Form Control Event Handler(s) -
private void btnDoSomeWork_Click(object sender, EventArgs e)
{
//Let's start our worker objects such that [0] finishes first, [2] second, and [1] third
oDoSomeWork[0].Count(10);
oDoSomeWork[1].Count(50);
oDoSomeWork[2].Count(20);
}
#endregion
#region - DoSomeWork Event Handlers -
//These worker event handlers check to make sure that they can handle the task on the proper thread
//Handle worker generated messages
public delegate void onMessage_delegate(PostMessageEvent messageHandler);
private event onMessage_delegate onMessage_event;
private void MainForm_OnMessage(PostMessageEvent messageHandler)
{
if (this.InvokeRequired == true)
{ BeginInvoke(onMessage_event, new object[] { messageHandler }); }
else
{ onMessage_method(messageHandler); }
}
private void onMessage_method(PostMessageEvent messageHandler)
{ UpdateMessage(messageHandler.strMessage); }
//Handle worker generated data
public delegate void onData_delegate(RaiseDataEvent dataEvent);
private event onData_delegate onData_event;
private void MainForm_OnData(RaiseDataEvent dataEvent)
{
if (this.InvokeRequired == true)
{ BeginInvoke(onData_event, new object[] { dataEvent }); }
else
{ onData_method(dataEvent); }
}
private void onData_method(RaiseDataEvent dataEvent)
{
UpdateMessage(dataEvent.Tag.ToString() + "; " + dataEvent.Data);
}
#endregion
#region - Update Message Function -
private void UpdateMessage(string Message)
{
//This message handler also checks to see if it is operating on the correct thread so as to
//not throw an exception
if (this.txtMessages.InvokeRequired)
{
SetMessageCallback d = new SetMessageCallback(UpdateMessage);
this.Invoke(d, new object[] { Message });
}
else
{ txtMessages.AppendText(DateTime.Now.ToString("HH:mm:ss") + "=> " + Message + "\r\n"); }
}
#endregion
}
}
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Delegate derives from MultiCastDelegate[^] so this is expected behavior.
I know the language. I've read a book. - _Madmatt
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Ok, do you have any advice on how to tie multiple & identical events to a single delegate method such that on any one event firing the delegate method can be made to execute only once?
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