C# Discussion Boards - CodeProject

Nish Nishant2-May-02 22:43

2-May-02 22:43

Colin Davies wrote:
Has anyone had any problem with unmanaged resources like handles etc ?

What do you mean by that? If you are writing a C# program, everything is managed. You can't access an unmanaged resource. Unless you meant something else.

Nish

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James T. Johnson2-May-02 22:44

2-May-02 22:44

An unmanaged resource is a file, database connection, HPEN, HDC, HBITMAP, etc... There are wrappers around all of those resources each providing you with a Dispose method which will free the handle; in the case of Files and Database Connections you have appropriate Close methods you can call as well.

James

Simplicity Rules!

Nish Nishant2-May-02 22:50

2-May-02 22:50

Thanks James. But my idea was that Dispose is automatically called. I wasn't aware that we need to call it manually. Unless we are talking of our own wrapper class.

Nish

Check out last week's Code Project posting stats presentation from :-
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Feel free to make your comments.

ColinDavies2-May-02 22:54

ColinDavies

2-May-02 22:54

My issue is what happens on exit ?
Since the poointer is hadling the addresses on the stack where will it be left ?
Then what happens if I run a new instance of the App ?

Regardz
Colin J Davies

Sonork ID 100.9197:Colin

More about me Smile | :)

Nish Nishant2-May-02 23:08

2-May-02 23:08

Irrespective of whether it's a .NET app or an unmanaged Win32 app, when a process terminates, all resources are freed.

Nish

Check out last week's Code Project posting stats presentation from :-
http://www.busterboy.org/codeproject/
Feel free to make your comments.

James T. Johnson2-May-02 22:58

2-May-02 22:58

Dispose isn't automatically called; the Finalize method is, at some point in time.

For handling nonmanaged resources Microsoft has come up with the Dispose pattern, classes that work with nonmanaged resources are supposed to implement IDisposable (only method is Dispose).

In side that the managed resources are released and the object should throw an exception if an attempt is made to use that instance again. Also inside of the Dispose method you should call GC.SuppressFinalize(this); so that the finalizer doesn't get called (no need since you already freed your resources). The finalizer is supposed to just call Dispose.

Confused yet? Big Grin | :-D

Enter the using construct. With it you can specify that an object will have its Dispose method called automatically.

using(Graphics g = CreateGraphics())<br />
{<br />
  // use g<br />
}

Roughly translates to

Graphics g = CreateGraphics();<br />
try<br />
{<br />
  // use g<br />
}<br />
finally<br />
{<br />
  ((IDisposable) g).Dispose();<br />
}

Simplicity Rules!

Nish Nishant2-May-02 23:08

2-May-02 23:08

Thanks a LOT James. I sorta understand now Smile | :)

Man, I wrote all that code and I never knew about all this inside stuff.
I feel a little silly

Nish

p.s, CG was telling us to stop bothering you with questions, so you can finish the saver Smile | :)

Check out last week's Code Project posting stats presentation from :-
http://www.busterboy.org/codeproject/
Feel free to make your comments.

James T. Johnson2-May-02 23:12

2-May-02 23:12

Nish [BusterBoy] wrote:
p.s, CG was telling us to stop bothering you with questions, so you can finish the saver

LOL, yeah I was busy writing my first reply when I was supposed to be seeing why the drawing didn't speed up even though my test program shows ~80% increase in drawing Smile | :)

James

Simplicity Rules!

James T. Johnson2-May-02 22:43

2-May-02 22:43

In WinForms there is a resource manager that is supposed to keep track of the resources for you, but I think its best practice to call free up resources right away.

If there is a managed wrapper for the resource just call Dispose on it to do that; else you'll have to dispose of it yourself.

James

Simplicity Rules!

ColinDavies2-May-02 22:52

ColinDavies

2-May-02 22:52

Thanks Mr Johnson,
I realised about the Dispose, but what happens if I don't use it and the user exits the App.
Is there a resource leak ?

Regardz
Colin J Davies

Sonork ID 100.9197:Colin

More about me Smile | :)

James T. Johnson2-May-02 23:08

Re: app.config in winforms

2-May-02 23:08

As I understand it, if you used objects handled by the Resource Manager it will free those for you; ones that aren't handled by it will get free'd if and only if their finalize method frees them.

James

Simplicity Rules!

app.config in winforms

2-May-02 18:26

does anyone know how to create this file (app.config) when working with winforms(it's similar to the web.conf in asp.net)? This file gets created with some projects but not others and I was not paying attention when it got create. I just noticed it one day and started adding keys to hold my connection string. But now I need to know how to create this file and I don't know how.

ez22-May-02 19:16

ez2

2-May-02 19:16

Whooya!!! This one took me forever to figure it out. Basically, select a control. Then select its properties. For most controls you will have either DataBinding or DynamicProperties section on the properties list. Go into Advance and select the items you want to place in the config file. An app.config file will automatically be generated.

Re: app.config in winforms

Corto Maltese2-May-02 19:41

Corto Maltese

2-May-02 19:41

You can create MyApp.exe.config in the same directory where your app resides,
and than use System.Configuration.ConfigurationSettings to read the configuration file app settings.

Config file example:
<configuration>
<appSettings>
<add key="Database" value="MyDB" />
<add key="Username" value="code" />
<add key="Password" value="project" />
</appSettings>
</configuration

-Gile

Re: app.config in winforms

Andres Manggini3-May-02 17:28

Andres Manggini

3-May-02 17:28

I've found this topic not well documented.. actually, I was playing with Custom Configuration Handlers, but it's related.

Ok, to the point Smile | :)

, every time you compile your program using Visual Studio .NET it will look for a file named app.config, if the file exists, it will create an output file on your destination directory (Release or debug for example) with the following name:

<ApplicationName>.exe.config

This file will contain the data you put on app.config.
Be aware that this file will be recreated everytime you compile your program (this got me for a while), so if you change the output config file, the changes will be lost on your next recompile.

If you need to change the config file during development, change app.config, you are going to see these changes reflected on your output file.

Hope this helps.

Andres Manggini.
Buenos Aires - Argentina.

Dumb Question !

Nick Parker2-May-02 16:18

Nick Parker

2-May-02 16:18

Ok, I know this must be a really dumb question, but how do I add an image to my project in Visual Studio.NET so that I can reference it in code such as "myPicture.jpg". Thanks again, don't laugh too much Smile | :)

Nick Parker

James T. Johnson2-May-02 17:14

2-May-02 17:14

So such thing as a dumb question Smile | :)

Right click on the project and choose Add Existing Item, select your jpg. Click on it in Solution Explorer then in the properties box change the Build Type from Content to Embedded Resource.

Now when you want to load it,

Bitmap myJPG = new Bitmap(GetType(), "myPicture.jpg"); assuming that the class is in the same assembly (ie project) as the jpg.

Good Luck,

James

Simplicity Rules!

Nick Parker2-May-02 17:32

Nick Parker

2-May-02 17:32

Thanks James, sometimes some of the easiest things aren't known by all, I just hope this helps someone else too.

Nick Parker

James T. Johnson2-May-02 17:48

2-May-02 17:48

I wouldn't classify it as the easiest thing to come up with; it took me about a day of working on my own to figure it out. And then I read it last week in Petzold's book Poke tongue | ;-P

James

Simplicity Rules!

Christian Graus2-May-02 17:33

Christian Graus

2-May-02 17:33

James T. Johnson wrote:
So such thing as a dumb question

Are you sure ? :P

This question was one that got me though, and I still don't think I fully have a handle on how to make it work. It just happens to work in the project I am working on, so I don't mess with it. Actually, I think someone else fixed it for me... Wink | ;)

Christian

The tragedy of cyberspace - that so much can travel so far, and yet mean so little.

And you don't spend much time with the opposite sex working day and night, unless the pizza delivery person happens to be young, cute, single and female. I can assure you, I've consumed more than a programmer's allotment of pizza, and these conditions have never aligned. - Christopher Duncan - 18/04/2002

James T. Johnson2-May-02 17:45

2-May-02 17:45

LOL, I just now saw that I mis-spelled 'No'

Christian Graus wrote:
Are you sure ?

No, I'm never sure of myself; to become sure makes me ignorant of other possibilities. I am confident in my answers though but I leave myself open to other solutions Smile | :)

Christian Graus wrote:
Actually, I think someone else fixed it for me...

Wonder who? Big Grin | :-D

I think when we've got the screensaver pretty hammered out I'll write an article on using resources. Then I need to write part two to Nish's Registry article Big Grin | :-D

James

Simplicity Rules!

Christian Graus2-May-02 17:51

Christian Graus

2-May-02 17:51

James T. Johnson wrote:
I think when we've got the screensaver pretty hammered out I'll write an article on using resources. Then I need to write part two to Nish's Registry article

I'd considered trying to hammer out a decent registry class. I still have my bottleneck detector code waiting for an article, as well. I'd like to get a decent article up on the screensaver as well, sometime soonish.

I'd love to read an article on using resources, I couldn't get that thing you did to put them into a subfolder to work at *all*.

Christian

The tragedy of cyberspace - that so much can travel so far, and yet mean so little.

And you don't spend much time with the opposite sex working day and night, unless the pizza delivery person happens to be young, cute, single and female. I can assure you, I've consumed more than a programmer's allotment of pizza, and these conditions have never aligned. - Christopher Duncan - 18/04/2002