C# Discussion Boards - CodeProject

leppie8-Aug-02 7:16

leppie

8-Aug-02 7:16

public delegate void EventHandler(int Index);
public EventHandler PressIcon;

This does however work. Although it looks not right, can some please explain what the difference is between the above and this below?

public delegate void EventHandler(int Index);
public event EventHandler PressIcon;
protected virtual void OnPressIcon(int index)
{   
   if (PressIcon != null) PressIcon(index);
}

I know options 2 is the "correct" way, but how does this differ?

Smile | :)

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Re: My very own events

Nnamdi Onyeyiri8-Aug-02 7:20

Nnamdi Onyeyiri

8-Aug-02 7:20

i think

1. The second give the user the ability to override what happens in that event in derived classes

2. if an event handler is not attached to PressIcon, then it will be called, but there will be no body, that is why the first gives an exception when the code is called, with no event handler attached.
get what i mean>?

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"All programmers are playwrights and all computers are lousy actors."

Re: My very own events

leppie8-Aug-02 7:52

leppie

8-Aug-02 7:52

Nnamdi Onyeyiri wrote:
if an event handler is not attached to PressIcon, then it will be called, but there will be no body, that is why the first gives an exception when the code is called, with no event handler attached.
get what i mean>?

You didnt note the changes ?? In example 1 i declare only a delegate, not an event delegate, thus the OnPressIcon function is not neccesary and u call the delegate directly.

In the implementation , u would just call "it" like u would for an event except u call the delegate directly. This works! But what are the differences between the two?

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Treeview Control on MDI Main Window

Eka8-Aug-02 1:52

Eka

8-Aug-02 1:52

Hi all,

I try to have a MDI application.
What I am trying to do is to make main window to have a treeview control in it. I want to place on left side of the main window. So, when a child window is opened and maximized it will occupy the rest of space on the main window.

How can you accomplish this?

ATM, i already tried, but when i maximized child window, it occupy the whole main window space.

Thanks for the help
Eka

Re: Treeview Control on MDI Main Window

James T. Johnson8-Aug-02 2:26

James T. Johnson

8-Aug-02 2:26

Set the TreeView's Dock property to DockStyle.Left, that should be all you need to do.

Assuming you set the child form's MdiParent property to the instance of the main form.

James

Open and Read a file

Trevor Vuong8-Aug-02 1:24

Trevor Vuong

8-Aug-02 1:24

Hi all,
I try to open and read from a text file but it always gives me error.
Code as followed: (the "UserList.lst" is the same dir with the exe which is
C:\Read\bin\Debug)

FileStream fs = new FileStream("UserList.lst", FileMode.Open);
StreamReader sr = new StreamReader(fs);

I get error on the first line which it says:
"Un unhandled exception of type 'System.IO.FileNotFoundException'

Additional information: Could not find file "C:\Read\bin\Debug\UserList.lst"

Can someone help me with this?
(The file UserList.lst is in that dir)

Thank you
NT

Re: Open and Read a file

leppie8-Aug-02 1:27

leppie

8-Aug-02 1:27

FileStream fs = File.Open(params...); or File.Create()

Smile | :)

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Re: Open and Read a file

8-Aug-02 1:45

Thanks Leppie actually my code or your code as shown work.
In windows XP, Explorer doesn't work the correct file extension.

Have a nice day Leppie.

Re: Open and Read a file

James T. Johnson8-Aug-02 2:39

James T. Johnson

8-Aug-02 2:39

Works fine here; perhaps the filename was mistyped?

James

Dockable form

Sam19798-Aug-02 0:15

Sam1979

8-Aug-02 0:15

I have made a windows form in C# and I want it to permanently be displayed on the computer desktop.All other applications should have open under it.What I mean is that any application which opens should have the desktop area below my form available to it.
My form is a small strip.

Re: Dockable form

leppie8-Aug-02 1:24

leppie

8-Aug-02 1:24

The TopMost property (of the form) set to true will do this Smile | :)

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Re: Dockable form

Anonymous8-Aug-02 18:30

Anonymous

8-Aug-02 18:30

With top most property the form will become the top- level window.I want this top level window to be dockable to the desktop.Something like the APPBAR.

Re: Dockable form

leppie8-Aug-02 22:43

leppie

8-Aug-02 22:43

You should have said that Smile | :)

But sorry i cant help with docking. I suggest looking at the magic library [^]'s source.

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Trouble w/ Multithreaded Windows Service Please Help

Aisha7-Aug-02 13:43

Aisha

7-Aug-02 13:43

Hi,
I wrote a multi-threaded application that sends/recieves documents on a scheduled/event driven basis. It works fine as a console application the files are being sent and the CPU usage is around 30%. My problem is when I have the exact same code in a Windows Service application. When the service is using one thread to send documents it also works fine, but if there is more than one thread running at one time the CPU usage shoots up to 100%. Could someone please help me? Confused | :confused:

Thanks

P.S. The applcation is also using the System.Timer and File System Watcher.
Thanks Again,

Aisha

BinaryWriter

Steven Behnke7-Aug-02 11:55

Steven Behnke

7-Aug-02 11:55

I am writing a client/server application with the server running on Linux written in C++ and the client application running on Windows XP written in C#. I am sending JPEG images over the network from cient to server and am getting some very odd behavior. It appears that after each JPEG I transmit I get about 1 - 3 packets containing 1 byte of useless information. Is this something with BinaryWriter that is it sending additional informaiton about what it sent?

Thanks,
Steven

Textbox input with the passwordchar

Bill Ferreira7-Aug-02 9:17

Bill Ferreira

7-Aug-02 9:17

I need to have a multiline textbox with a passwordchar. I know that the passwordchar property will not work in multiline mode. So, I figure on capturing the keypress event to create the same effect but there is one problem: -

I can't figure out how to substitute the '*' character for the key pressed. Everything is read only.

Thanks,
Bill Ferreia

Re: Textbox input with the passwordchar

Nnamdi Onyeyiri7-Aug-02 21:49

Nnamdi Onyeyiri

7-Aug-02 21:49

every time you enter into the textbox, the TextChanged Event is called, maybe u could do something there?

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"All programmers are playwrights and all computers are lousy actors."

Solutions with multiple projects

Bill Ferreira7-Aug-02 9:11

Bill Ferreira

7-Aug-02 9:11

Say you have two projects written in different .NET languages (C#.NET, MC++.NET) How do you reference the classes of the MC++.NET in the C#.NET project?

I don't have any problems importing the projects into the solution, but I can't figure how to reference the classes.

Thanks,
Bill Ferreira

Re: Solutions with multiple projects

Nnamdi Onyeyiri7-Aug-02 21:50

Nnamdi Onyeyiri

7-Aug-02 21:50

is the MC++ code in a DLL? im not sure if you can then just reference it as u would a c# dll - ull have to try.

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"All programmers are playwrights and all computers are lousy actors."

Centering Message Boxs - How?

Joel Matthias6-Aug-02 7:33

Joel Matthias

6-Aug-02 7:33

How do I center a message box to my application form. I have tried passing the application form as the parent of the message box but it still appers centered to the desktop.

MessageBox.Show(myForm, ...);

Joel

Is there a vertical scrollbar?

Nnamdi Onyeyiri6-Aug-02 7:11

Nnamdi Onyeyiri

6-Aug-02 7:11

I need to know if there is a vertical scrollbar in a listbox. there is a bool HorizontalScrollBar property, but not a bool VerticalScrollBar

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"All programmers are playwrights and all computers are lousy actors."

Re: Is there a vertical scrollbar?

Luis Alonso Ramos7-Aug-02 7:19

Luis Alonso Ramos

7-Aug-02 7:19

You have ItemHeight (in pixels) and Height of the control... so you can try something like:

<br />
bool bVertScrollBar = lb.ItemHeight * lb.Items.Count > lb.Height;<br />

Just take into account that you can change the units of your form (with AutoScaleBaseSize).

-- LuisR

p.s. And take into account that the horizontal scroll bar could be displayed also, thus reducing the height of the display area.

──────────────
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  Chihuahua, Mexico
  www.luisalonsoramos.com

"Do not worry about your difficulties in mathematics, I assure you that mine are greater." -- Albert Einstein

Re: Is there a vertical scrollbar?

Nnamdi Onyeyiri7-Aug-02 7:37

Nnamdi Onyeyiri

7-Aug-02 7:37

thats sort of what i did - except there is a property called PreferedHeight thats does your multiplication for you, and its better to use it, because not all the items in the listbox are the same height.

Suspicious | :suss: Email: theeclypse@hotmail.com URL: http://www.onyeyiri.co.uk
"All programmers are playwrights and all computers are lousy actors."

Returning by Ref

gekoscan6-Aug-02 6:35

gekoscan

6-Aug-02 6:35

I am interested in returning a value by reference so that if it is an ArrayList when I make changes to it, the changes are permanent.

Now this is totally possible in C++ and I used to do it all the time.

ie. public &int Class1::Foo()

This must be possible in C#, is there something I am missing?????

Thanks very much...

Re: Returning by Ref

Nnamdi Onyeyiri6-Aug-02 7:10

Nnamdi Onyeyiri

6-Aug-02 7:10

you can do the same thing is C# - except, you have to declare the code as unsafe

e.g.

unsafe public &int Method()

and you need to compile with the 'comile unsafe code' compiler switch. I believe it is like this because when you do this, you are overrideing the .NET memory management, so you are handling the memory yourself or sumpthin.

p.s. to use it in normal code, just do this:

...
unsafe
{
   ....
}

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"All programmers are playwrights and all computers are lousy actors."

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