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I think you have a misconception of what event handlers are.
An event handler is just a callback (look up 'delegate' on MSDN) that is called by the class that publishes the event.
Each event handler has a certain signature, usually containing the object calling the delegate and an additional object holding some additional information for the event.
The Click event of System.Windows.Forms.Button (or rather the matching event handler delegate System.EventHandler) has such a signature. Because System.Windows.Forms.Button calls the delegate you give it, there's nothing you can do to modify the signature of the delegate there.
So you'd have to derive from Button and override the Click event not to require an event handler of type EventHandler but one of type MyNewEventHandler.
This delegate would be declared like this:
public delegate void MyNewEventHandler(object sender, System.EventArgs e, int something, bool whatever);
In your derived class you'll have to fire your new Click event by calling the event handlers attached to your new button class.
You see, it's not quite as easy as you might expect.
Are you sure your button can (or should) provide the additional information in the Click event? Are something and whatever really different with each click?
If not then you shouldn't change the event handler signature for something as basic as a click event.
Mav
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An easier way is to keep the parameters something and whatever, for example, as fields in your class. In your current example, the handler is executed in the same thread and on the same instance so storing this data as fields on your class isn't a problem. This would be a much simpler way of doing it - and is very common through both the .NET BCL and many other applications - than defining your own event for a Button derivative.
Other than that, mav.northwind is right. A handler must use the same signature as the delegate that defines the event.
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Software Design Engineer
Developer Division Sustained Engineering
Microsoft
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i need to create a Byte array of lenght 300000...
i can't do that:
Byte[300000] myByte;
so how can i do?
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Byte[] bytes = new Byte[300000];
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How do I get the current logged in user name of a remote nt machine?
I know there is a way in delphi, but how to master it in C#, may be with an API call?!
Looking forward to some answers.
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Do you mean the user that's logged into a remote machine, or a remote user logged into your machine? How did you do it in Delphi? If you used a native API then you can do the same thing in C#. Read about Consuming Unmanaged DLL Functions[^] in the .NET Framework SDK, and see http://pinvoke.net[^] for many common method signatures.
You can also use WMI, for which classes are defined in the System.Management namespace. Read Accessing Management Information with System.Management[^] also in the .NET Framework SDK.
This posting is provided "AS IS" with no warranties, and confers no rights.
Software Design Engineer
Developer Division Sustained Engineering
Microsoft
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Hi all!
I'm supposed to create an MMC snap-in in C# for XP/Win2000.
As far as I've seen, there is no support for this in C#. And most of the time people recommend the framewok of IronRingSoftware as a great starting point.
Now I wonder, if I'm adding a reference to Microsoft Management Console 2.0 in the Visual Studio IDE (Add Reference -> COM tab -> Microsoft Management Console 2.0), what am I referencing? By doing this I can write MMC20. in the code window, and a list of interfaces and methods appear.
Is this reference useful for creating snap-ins?
If this is a way of building snap-ins, what is the difference between the MMC reference and the framework from IronRingSoftware?
Thanx in advance 
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esjq wrote:
Is this reference useful for creating snap-ins?
It's necessary. MMC is a COM client, and snap-ins are COM servers. .NET can communicate with COM using Runtime Callable Wrappers (RCWs) to consume COM components, and with COM-Callable Wrappers (CCWs) to expose managed component to COM. You're actually doing both. You must implement those interfaces defined in that interop assembly you created, and register your assembly with regasm.exe.
There are rules to exposing your managed components to COM. NEver use auto-generated interfaces, and in this case you wouldn't have to because it's the interfaces defined in that interop assembly that you're implementing. This means, on your classes, you set ClassInterfaceAttribute to ClassInterfaceType.None. Always attribute your classes and interfaces - if you define any - with a unique GuidAttribute that you do not change. Never change published interfaces. These are all rules for writing COM components and must be followed when exposing managed components to COM, otherwise your COM clients (like MMC) will never find your components (because the CLSID, or class ID - a GUID for your classes keeps changing) or because the interfaces IDs (IIDs) keep changing. Read Design Considerations for Interoperability[^] in the .NET Framework SDK, as well as Exposing .NET Components to COM[^] for more information about this topic.
Code Project has some good articles about developing MMC snap-ins, including how to do it in managed code. Creating MMC Snapin using C# (Part I)[^] is one such example. You can search for others.
You should also read the MMC Programmer's Guide[^], which takes you through developing a snap-in (using native COM, but the information is still very much applicable since you'll be implementing the native interfaces in your managed code using the interop assembly).
This posting is provided "AS IS" with no warranties, and confers no rights.
Software Design Engineer
Developer Division Sustained Engineering
Microsoft
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Thank you! Really appreciate the information and the links.
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this is my code...why it doesn't update changes to my datasource???
void MenuItem3Click(object sender, System.EventArgs e)
{
MyConn = new OdbcConnection(myConnectionString);
string SQL = "SELECT * FROM novice ORDER BY id_novice DESC";
OdbcDataAdapter myCommand = new OdbcDataAdapter(SQL,MyConn);
myCommand.SelectCommand = new OdbcCommand(SQL, MyConn);
DataSet ds = new DataSet();
myCommand.Fill(ds, "novice");
OdbcCommandBuilder custCB = new OdbcCommandBuilder(myCommand);
BindingManagerBase cm = BindingContext[dataGrid1.DataSource] ;
DataRowView drv = (DataRowView )cm.Current ;
((DataRow )drv.Row).Delete () ;
myCommand.Update(ds, "novice");
ds.AcceptChanges();
}
________________________
live and die by the code
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IMO, to call an OdbcDataAdapter instance myCommand is confusing. You should - following suggested naming guidelines in the .NET Framework sDK - use myAdapter at the very least. Something even more descriptive than that, using "adapter" somewhere, would even be better.
Also, while not the problem, calling ds.AcceptChanges() is not necessary. The Update method does this for you upon successful completion of updating the data store (i.e., no exceptions are thrown).
You should try debugging the code to make sure that the OdbcCommandBuilder constructed suitable SQL statements for each of OdbcDataAdapter's properties besides the SelectCommand which you've already defined (and is required for the command builder).
Are you sure that the DataSet is full and that all the data is in the "novice" DataTable? At times you have to set up OdbcDataAdapter.TableMappings if the table from which you're selecting doesn't result in the table name you expect. This is a problem with SQL Server, which names it's tables (result sets) "Table", "Table1", "Table2", and so on.
I also assume that the BindingContext code is elsewhere, perhaps as part of a Button.Click handler? Make sure that however you bind your data, you use the same exact approach to get the BindingContext. To eliminate any problems, it's recommended that you use the following:
CurrencyManager cm = (CurrencyManager)dataGrid1.BindingContext[
dataGrid1.DataSource, dataGrid1.DataMember</code>]; This ensures that if you set only DataSource to a DataTable, or set the DataSource to the DataSet and the DataMember to the table name (which is recommended for data navigation or to support multiple table views if binding multiple tables throughout the lifetime of that particular DataGrid), that either works. The binding context must be exactly the same as how you bound your data, or it will not work.
Finally, debug your application or add some debugging code to make sure that the DataSet actually includes changes (which could be a result of not binding correctly, as I stated above). You can do this easy by using DataSet changes = ds.GetChanges();</pre>That will filter out all the unchanged data so you don't have to sift through so much, since examining <code>DataSets in the variables windows is difficult (Whidbey, i.e. Visual Studio 2005, will improve this with debugging viewers for various types of objects, which is also extensible for your own objects).
This posting is provided "AS IS" with no warranties, and confers no rights.
Software Design Engineer
Developer Division Sustained Engineering
Microsoft
[My Articles] [My Blog]
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Hello!
I have a problem, and nobody seems to know the remedy...
There are a lot of programmes capable of editing (doing various things) custom file formats, for example game editors.
For instance, there is a fifaFS console application which gives the oppurtunity of editing .big graphic archives of FIFA 2005 from EA Sports. You can pack, unpack files, rebuild etc.
So how did the creator manage to write such software? I mean, there is nothing in Delphi capable of editing .big files (it's written in Deplhi, but I am a C# programmer so I want to know how to do it in C#)... So how?!
I heard that you need to know the structure of the file... Ok, so for example I have the file specification of BMP file format.
But how do I do stuff with it? Please explain! And please give some piece of code... I really need your help!
Please don't tell me that .big is a commercial file format owned by EA, so there's no chance of editing it. I know at least 20 programmes capable of editing .big file.
Thanks!
Regards,
Lars
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I dont htink there is anything magical with this file format. I think its just something where several files are packed into a single file. At the beginning of those files one can clearly the the contents.
You could just dig through one sample file and try to findout yourself how exactly it works. You could also contact someone from one of those 20 programs and ask him if he has any infos conecrning the exact format.
So it doesnt have to do anything with the programming language uyou use, but with the knwoledge you have of the format. If you know it a simple stream is enough to unpack the contents.
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Yeah, well, thanks, but I am kind of a begginer...
So could anyone please give an example code for the available BMP file format, just to demonstrate the technique? Please!
The BMP specification is here: http://www.dcs.ed.ac.uk/home/mxr/gfx/2d/BMP.txt
Or just type 'File formats' in Google, then check out the first site. Choose whichever file you like, and please help me!
Thanks!
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It won't help much if someone shows you how to read file format A (for example, BMP) if you want to modify file format B.
When you get down to it, each file is just a bunch of bytes you can read or write (check BinaryReader or BinaryWriter in the FCL, for example).
But unless you get the specification _what_ the bytes at a certain offset mean, you're out of luck.
You might be able to scan for certain byte patterns, but usually when you try to modify a file without knowing the exact structure you'll end up with a corrupt file.
Once you have the structure you can write classes that read or write the correct files, but not any sooner.
mav
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Ok, thanks! But you didn't get it: I don't want to edit those .big files, I just stated them as an example. I just want to understand how does one edit some file format. And I wanted some simple code about working with those bytes...
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Editing the file format meaning understanding exactly what each byte in the format means. There is no one method for editing every file format. You read the file stream in, parse it up based on the rules for the file format, edit it based on the rules of the file format, and then write it back out.
Are you asking how to read a file? How to parse up the data? or what?
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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I would manage all the inputText of Internet Explorer and InputBox of other running software by my Program, so iif the user make right click on the input it shows the normal windows contextmenu cut/copy/delete but with a new vox relative to my program, infact if cliccked it call my program and it can return a text to put autmatically inside...
Yes it is a bit complicated but can you help me to understand how to do?
Thanks.
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With a new "vox"? (Voice activation?) Could you elaborate?
You can interact with both the WebBrowser control (which is actually Internet Explorer) or a running instance (or create a new instance if none already exist) of the InternetExplorer class by creating an RCW (Runtime Callable Wrapper) from shdocvw.dll, which you can do using either tlbimp.exe from the .NET Framework SDK, or by importing a COM reference to "Microsoft Internet Controls" using the COM tab when you click "Add Reference..." for your project.
You should search this site for "WebBrowser" or "InternetExplorer" (no space, since it's a class name). There are lots of articles about hosting the WebBrowser control in Windows Forms, as well as advanced hosting interfaces. Either way allows you to handle when documents are loaded, then walk the document object model (DOM) using the WebBrowser.Document property and casting it to the mshtml.IHTMLDocument2, which is defined in the Microsoft.mshtml.dll assembly that should've installed with VS.NET (and a number of other applications, or you can create your own from mshtml.dll as well). Walking the DOM is just like scripting a DHTML document, only with a little bit of extra work (and believe me, a lot less than with native C++ code) to cast objects to interfaces that implement the property or method you seek, which script does automatically).
You can also do this using the InternetExplorer class to automate a running instance of IE.
You could also implement a toolbar using managed code (though this isn't recommended as it will significantly increase the working set - amount of memory allocated to the process - for whatever process is hosting the WebBrowser control, be it iexplore.exe, explorer.exe (Windows Shell), or some other process). There are articles about that here on Code Project as well, if you'd only search. Try searching for "IE toolbar".
To search this site, use the text box at the top of every page underneath the logo.
This posting is provided "AS IS" with no warranties, and confers no rights.
Software Design Engineer
Developer Division Sustained Engineering
Microsoft
[My Articles] [My Blog]
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Hello,
I'm new to the C# language but I'm trying to build a little app that will let me monitor to see if my computer is making HTTP/FTP/UNC requests to the outside world. I was just wondering how I can start on this? Is there a System namespace or class that I can use??
Thank you very much,
Troy
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does anyone know how to start this one?
thanks
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I'm wondering what the best threadsafe way to create and use general purpose routines like special date functions, special user calculations, etc. Up until now, what I have been doing is to create a file call myutils.cs that looks something like the code below. I can call it without instantiating it because it is static which is very convienient. I am calling these routine from multiple threads and my app is crashing so I'm concerned I may have made a fatal mistake.
Could someone enlighten me please if what I am doing is major bad? Or, possibly suggest a better way to do the common things.
Thanks
Peter
public class PolarUtils
{
public static int[] HillsForUser(string currentUserId)
{
SqlConnection sqlConnection = PolarUtils.GetNewSqlConnection();
sqlConnection.Open();
string sqlSelectString = "SELECT id_hill FROM HillFile ";
sqlSelectString += " WHERE UserId = '" + currentUserId + "'";
SqlCommand sqlCom
...
public static SqlConnection GetNewSqlConnection()
{
SqlConnection sqlConnection1 = new SqlConnection();
string str = null;
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Within the same AppDomain, access to static members is serialized so they are automatically thread-safe.
What is the exception that is thrown. Saying "my application crashes" is hardly specific enough to provide you with any decent amount of help.
This posting is provided "AS IS" with no warranties, and confers no rights.
Software Design Engineer
Developer Division Sustained Engineering
Microsoft
[My Articles] [My Blog]
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This may be obvious, but does that mean that static members act like critical sections in that access from another thread will be automatically blocked until the current thread exits that static method? If so, that's great to know. If possible, could you point me to a link where I can read more about it?
Thanks again for both answers,
-Peter
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