Re: CRC check - C# Discussion Boards

Re: Retrieve machine names and/or IP's ..?

Heath Stewart5-Jul-04 6:17

5-Jul-04 6:17

This has been asked far too many times on this forum. Please search[^] the forums first before posting. Every forum has a "Search comments" link directly above the message board itself and you can even search multiple forums at once.

Microsoft MVP, Visual C#
My Articles

IDisposable, destructors and loaded assemblies

Boaz V3-Jul-04 5:01

Boaz V

3-Jul-04 5:01

Hi,
in my program, at the constructor of the main driver class, it loads about 6 DLLs (managed) using the Assembly.LoadFile method and then invoking the needed
methods using reflections functions.
Anyway, when i want to quit the program, sometimes some of the dlls can not be accessed since "they are in use by another program". I've checked the Windows Task Manager and my process do not appear there... any ideas guys?

i thought maybe using Dispose procedure or a destructor. can anyone help me with deciding which road to take? and how?

10x

Re: IDisposable, destructors and loaded assemblies

KevinMac4-Jul-04 9:27

KevinMac

4-Jul-04 9:27

Don't know if this will help but I have started taking advantage of the "Using" keyword to automatically fire the dispose method. The feature is specific to C# as far as I know. You have to be sure the type you are using implements the IDisposable or it will throw a compile time error.

public void YourMethod()
{
using(MyObj m = new MyObj())
{
MyObj.DoWhatYouWant()
// Dispose() is called automatically for you when the
// Using block exits
}
}

Good luck and I hope it helps.

double buffering

blankg3-Jul-04 4:43

blankg

3-Jul-04 4:43

i extended textBox and set its styles to:
SetStyle(ControlStyles.UserPaint, true);
SetStyle(ControlStyles.AllPaintingInWmPaint, true);
SetStyle(ControlStyles.DoubleBuffer,true);
to avoid flickering, but now the text i enterd doesnt show in the textbox,
i noticed that ControlStyles.AllPaintingInWmPaint is the cause,
how can i overcome this problem and still avoid flickering?

Re: double buffering

Heath Stewart5-Jul-04 6:23

Heath Stewart

5-Jul-04 6:23

First of all, the ControlStyles enumeration is attributed with the FlagsAttributE (and any enumeration in the .NET base class library that is plural always does, as should other libraries when the developers follow naming guidelines), so the three lines (resulting in 3 * 4 = 12 instructions) can be done in one line (4 instructions):

SetStyle(ControlStyles.UserPaint | ControlStyles.DoubleBuffer
  | ControlStyles.AllPaintingInWmPaint, true);

This is far more efficient.

Second, when you specify these parameters you must override OnPaint and paint the text yourself. The documentation for these UserPaint and <code.allpaintinginwmpaint< code=""> state this.

Third, the <code>TextBox's text is not painted by .NET. Almost every control in Windows Forms (in the .NET BCL) wraps the native common controls equivalent. You should not try to draw these yourself because they aren't not drawn by .NET, but by Windows itself.

Microsoft MVP, Visual C#
My Articles

CRC check

kratchkov3-Jul-04 3:51

kratchkov

3-Jul-04 3:51

Hi
Does someone know a fast method to get CRCs or Hashes of files, in order to compare two files?

thanks

----------------------
Instead of printing "No errors have been found", a compiler should rather print "None of your errors have been found", which would be, in most cases, true.

Re: CRC check

Paul Lyons3-Jul-04 4:38

Paul Lyons

3-Jul-04 4:38

Try this[^]Knowlege Base article.

Paul Lyons, CCPL
Certified Code Project Lurker

Re: CRC check

Vega023-Jul-04 4:39

Vega02

3-Jul-04 4:39

Check out the HashAlgorithm.ComputeHash() Method. Open a Stream on the file you want to input and this method will give you the hash.

Note that the HashAlgorithm Class is an abstract class. You probably want the derived class MD5CryptoServiceProvider. MD5 hashes are very reliable for your needs.

~L Smile | :)

using System.Runtime.Serialization.Formatters.Soap;

ABean2-Jul-04 23:49

ABean

2-Jul-04 23:49

I get the following message:

The type or namespace name 'Soap' does not exist in the class or namespace 'System.Runtime.Serialization.Formatters' (are you missing an assembly reference?)

On this line here:
using System.Runtime.Serialization.Formatters.Soap;

What am I missing or has something chnaged in .NET 1.1?

(I'm trying to use the BaseSerializable class in this article: http://codeproject.com/soap/soapseraialize.asp )

Re: using System.Runtime.Serialization.Formatters.Soap;

Colin Angus Mackay3-Jul-04 0:38

Colin Angus Mackay

3-Jul-04 0:38

I think the answer is in your question:

ABean wrote:
(are you missing an assembly reference?)

According to the MSDN Help for System.Runtime.Serialization.Formatters.Soap.SoapFormatter Class[^] you need to reference the assembly System.Runtime.Serialization.Formatters.Soap (see the requirements section at the bottom of the page)

To add a reference to this assembly in your project right click the requirements node under the project in the solution explorer and select Add Reference... Find the reference to the above assembly and add it.

Does this help?

"You can have everything in life you want if you will just help enough other people get what they want." --Zig Ziglar

The Second EuroCPian Event will be in Brussels on the 4th of September

Can't manage to P/Invoke that Win32 API in .NET? Why not do interop the wiki way!

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TextBox at run time

saud_a_k2-Jul-04 22:52

saud_a_k

2-Jul-04 22:52

I want to add textBoxes at run time into a groupbox (not on the form). How do I get points on the form and into the groupbox
And
How do I disable the right click menu got when right clicking in a TextBox.
(The cut, copy paste.. menu) .
pls help.

_____________________________________________________
Believe! Every thing has a purpose

Re: TextBox at run time

Stefan Troschuetz3-Jul-04 13:16

Stefan Troschuetz

3-Jul-04 13:16

To add controls to your groupbox call the Add or AddRange methods of its Controls property.

this.groupBox1.Controls.AddRange(new System.Windows.Forms.Control[] {this.textBox1});

Re: TextBox at run time

saud_a_k5-Jul-04 2:18

saud_a_k

5-Jul-04 2:18

thanx,
and,
How do I disable the right click menu got when right clicking in a TextBox.
(The cut, copy paste.. menu) .
pls help.

_____________________________________________________
Believe! Every thing has a purpose

Re: TextBox at run time

Stefan Troschuetz5-Jul-04 2:53

Stefan Troschuetz

5-Jul-04 2:53

I don't know exactly how to disable the menu.

At first I thought this could be done by setting the ContextMenu property to null but a quick trial showed no success.
Furthermore I can only guess what maybe works.

Try to override the WndProc method of either the form which contains your textbox or of a derivation of the TextBox class. There you may be able to catch and dispose the message which triggers the display of context menu.

Design Issue

hatim_ali2-Jul-04 18:14

hatim_ali

2-Jul-04 18:14

Hi,

I've subclassed two classes inside classA. Theses subclasses are derived from classA. There are some virtual functions in classA with their implementation defined in those subclasses. Client can only see classA. Instances of classA will be created by a class factory. On basis of parameters passed to class factory, the factory creates new objects of subclasses and returns them to client. Following snippet demonstrates the idea.

public class classA
{
/* some non-virtual functions with implementation defined */
/* some virtual functions with implementation defined in subclasses */

internal class subclass1 : classA
{
/* implementation of virtual functions declared in class A */
}

internal class subclass2 : classA
{
/* implementation of virtual functions declared in class A */
}
}

1) I want to run subclass1 objects into COM+ transaction. Is it possible because client never sees subclass1 although it uses subclass1. If possible how ??

2) Is it a good practice to do things this way. The idea behind was to provide client smplicity of using one class while acheiving the logical seperation at the backend for developer's ease.

Thanks in advance,

Regards,
Hatim Ali.

advantage of interface/abstract class

xcavin2-Jul-04 18:12

xcavin

2-Jul-04 18:12

wot is that an abstract class can do that interface cannot and viceversa ?

Re: advantage of interface/abstract class

Ray Cassick2-Jul-04 18:21

Ray Cassick

2-Jul-04 18:21

An abstract base class can provide some actual implimentation code, and Interface definition cannot.

Paul Watson wrote:
"At the end of the day it is what you produce that counts, not how many doctorates you have on the wall."
George Carlin wrote:
"Don't sweat the petty things, and don't pet the sweaty things."
Jörgen Sigvardsson wrote:
If the physicists find a universal theory describing the laws of universe, I'm sure the a**hole constant will be an integral part of that theory.

Re: advantage of interface/abstract class

xcavin2-Jul-04 23:34

xcavin

2-Jul-04 23:34

Is this the only point. Then y did they introduced a new term without one facility.

Re: advantage of interface/abstract class

Vega023-Jul-04 4:30

Vega02

3-Jul-04 4:30

Remember that when a new class is defined, it can inherit from only one base class. There are no restrictions on the amount of interfaces that the class can support.

For example, consider the Arraylist Class from the .NET Framework. This class implements four different interfaces: IList, ICollection, IEnumerable, and ICloneable. By using interfaces instead of a base class, a coder may treat it as a list, a collection, an enumerable collection, and a cloneable object, whichever he sees fit.

As another example, consider two classes Amoeba and Dog. Say that Amoeba derives from Unicellular since it is so simple and that Dog derives from Mammal. Both creatures need to Eat(), but because they do so in fundamentally different ways it makes no sense to provide Eat() in a base class common to both. A much better solution would be for them to both implement IMustEat, which forces them to have an Eat() function. IMustEat (an interface) does not define how - or even if - an Eat() method works. All it says is that an Eat() method must exist.

Remember that if not explicitly specified, a class derives from System.Object. The Object Class is very elementary and provides almost no functionality. On the other hand, implementing an interface allows you to make contractual guarantees about your class.

Hope this helps!

DataGrid & ArrayList

bmasephol2-Jul-04 11:03

bmasephol

2-Jul-04 11:03

Ok heres the scoop... I'm binding an arraylist of objects to a datagrid. I've got the data to show up by implementing the properties for my object. I've got my datagridtablestyles setup and working right. Things are going good... now I need to know how to add a new row. When I used a dataset with the datagrid there was always a "blank" line at the bottom you could just start typing in. I'm afriad that this was a implementation of the dataset and not the datagrid. So my question. How can I create that same functionality with my ArrayList of ojbects. Or what is my best method of adding new "rows" to my datagrid.

Thanks
Bryan

Datagrid Navigation

IamADotNetGuy2-Jul-04 7:30

IamADotNetGuy

2-Jul-04 7:30

Is there a way I can retain the selected values by using checkboxes while navigating between pages in the datagid control?

For eg: If i check one row and i will go to next page of the grid if I come back i want to retain the checked valued with checkbox checked...

I am using normal paging....

Re: Datagrid Navigation

saud_a_k2-Jul-04 20:07

saud_a_k

2-Jul-04 20:07

Please check here
http://www.syncfusion.com/FAQ/WinForms/FAQ_c44c.asp

_____________________________________________________
Believe! Every thing has a purpose

Question on events and local variables

Flack2-Jul-04 7:14

Flack

2-Jul-04 7:14

Hello,

In a button click method I create an EventLog, set its EnableRaisingEvents property to true and attach an event handler for the EntryWritten event.

<br />
EventLog eventLog = new EventLog(cbEventLogs.Text,txtMachineName.Text);<br />
<br />
			if(this.txtMachineName.Text == SystemInformation.ComputerName)<br />
			{<br />
				eventLog.EnableRaisingEvents = true;<br />
				eventLog.EntryWritten += new EntryWrittenEventHandler(eventLog_EntryWritten);<br />
}<br />

My question is, how does the event still get fired when you exit the button click method where the event log was created? Doesn't the EventLog variable fall out of scope when the method exits, causing it to be garbage collected?

Thanx for the help,
-Flack

Re: Question on events and local variables

Karl 20002-Jul-04 9:10

Karl 2000

2-Jul-04 9:10

The garbage collector will only collect when there reference count goes down to 0. By subscribing eventLog_EntryWritten to the EntryWritten event you are creating a reference. That reference is enough to keep the eventLog alive. Even though you no longer hold a reference one does exist. To get the garbage collector to collect the EventLog unsubscribe the event before eventLog goes out of scope and you no longer have control of any of the references to it.

Karl Baum
CEO of KGB Technologies
Specializing in custom software development.

Saving BMP/JPEG from Stream

Emiliano2-Jul-04 6:53

Emiliano

2-Jul-04 6:53

Hello,

I know this is the c# section, so my managed c++ code might be in the wrong place, but i know that the .net classes are the same in c++ or c# and all the code samples i have used are in c# and the logic is the same

I am trying to save an image stream into a .bmp file or a jpeg file. I an trying to use the .NET classes in the System::Drawing namespaces.

I have some code like the following

//preaper the bufferchar* buf = new char[bufSize];<br />
//populate the buffer with raw bytes coming from the video Stream<br />
dev->Grab(buf);<br />
Byte b[] = new Byte[bufSize];<br />
MemoryStream *ms = new MemoryStream( b );<br />
for(int i=0; i{    <br />
b[i]=buf[i];<br />
}<br />
Bitmap *b = new Bitamp( ms ); <br />
b->Save(S"C:\\test.jpg", ImageFormat::Jpeg);

Every time i run the code the following line
Bitmap *b = new Bitamp( ms );
throws a ArgumentException:Invalid Parameter used exception.

Does any one Know Why, could it be that the Bitmap class understands that the stream is not a valid image yet because the stream only contains the row bytes... any help please...

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