C# Discussion Boards - CodeProject

Re: Collection class with different class members

pxp1-Jul-04 4:05

1-Jul-04 4:05

Various approaches to the same goal, but just what's best shall vary in cases.

The VB logic i brought up was about the same logic. It's collection sonsists of objects. Why did i not know that one can add an object to a collection :P

Thanks for the info.

variable object names

rturner00329-Jun-04 20:13

rturner003

29-Jun-04 20:13

I need to create an unknown number of objects, for example DataReaders at runtime. In c# how would I create these names so that the first is dtrFred1 and the next is dtrFred2 etc. Obvisiuosly this will be in the form of a loop. In JScrpit/JavaScript one could use the eval() command, how is this achieved in c#

Robert T Turner
South Gloucestershire Council

Re: variable object names

Colin Angus Mackay29-Jun-04 20:49

Colin Angus Mackay

29-Jun-04 20:49

You could hold them in a suitable collection. For instance you can use a Hashtable, where the key is "dtrFred1" etc. and the value is the DataReader.

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!

My Blog

Re: variable object names

Nick Parker30-Jun-04 3:15

Nick Parker

30-Jun-04 3:15

Just to add with what Colin said, I would recommend you look into a class factory for generating your objects. Read this for further information: Abstract factory pattern[^]

- Nick Parker
My Blog | My Articles

CPU time consuming program

Mikke_x29-Jun-04 19:45

Mikke_x

29-Jun-04 19:45

Hello!
We are developing a program in c#, we have a problem with probably the threading. After a few minutes running our program, it starts to consume all cpu time, we have not started any own threads.
The running thread does not seem to have any priority, it does not slow down any other programs, it just overrides the idle thread, it seems.

Does anyone know of any known problem using c# concering out problem, or has any other ideas of what the problem might be.

M

Re: CPU time consuming program

Colin Angus Mackay29-Jun-04 20:42

Colin Angus Mackay

29-Jun-04 20:42

Mikke_x wrote:
After a few minutes running our program, it starts to consume all cpu time, we have not started any own threads.
The running thread does not seem to have any priority, it does not slow down any other programs, it just overrides the idle thread, it seems.

The idle thread is the lowest of the low in terms of priority. Of course your application will override it - it is supposed to do that. The idle thread is just what the OS does when it has nothing else to do. As your application is doing something the OS is therefore not, by definition, idle.

Re: CPU time consuming program

Mikke_x30-Jun-04 6:16

Mikke_x

30-Jun-04 6:16

Yeah of course. The problem here was that the process used 99% of the processor all the time. Altough it looked like it had really low priority since it did only use the processor if no other thread wanted to execute.

We did resolve the problem however. Can´t really explain the reason behind the problem, but it was because of a sleeping thread. We started a thread when we started the application and suspended it immedediately. Now we have changed it so that we don´t start the thread until we need it instead of starting it and suspend it from the start.

M

Treeview count parents

saud_a_k29-Jun-04 19:40

saud_a_k

29-Jun-04 19:40

I have made a Treeview, I add only parents.. no child.. I can do that, but the problem is in counting the no. of parents.. I have declared an array, called child[5,100] , I intend to count the no. of parents and associated children. my code for adding parent

string node1;<br />
           node1=Convert.ToString("RuleSet No." + (p+1).ToString());           <br />
           if(p>=5)<br />
           {<br />
               MessageBox.Show("YOU CAN ADD ONLY 5 ROOT NODES!!!");    <br />
           }<br />
           else<br />
           {<br />
               if (ruletree.Nodes.Count<=0)<br />
               {<br />
                   p++;<br />
                   this.ruletree.Nodes.Add(node1);<br />
                   child[p,0]=p;<br />
               }<br />
               else<br />
               {<br />
                   <br />
                   int nop=ruletree.Nodes.Count;<br />
                   p=nop;<br />
                   child[p,0]=p;<br />
                   p++;<br />
                   this.ruletree.Nodes.Add(node1);     <br />
               }

the peob. is that it counts the second parent as the third.. and hence..
HELP!

_____________________________________________________
Believe! Every thing has a purpose

oops.. I got it

saud_a_k29-Jun-04 19:45

saud_a_k

29-Jun-04 19:45

Sorry to bother you people.. I got it ..
just a '--' did the job..
sorry Hmmm | :|

_____________________________________________________
Believe! Every thing has a purpose

Ok One more question people

saud_a_k29-Jun-04 19:57

saud_a_k

29-Jun-04 19:57

How do I disable the selection of a particular node in a tree..
Eg. I don't want to add children to nodes already children.. I can show a messege box.. or do a no-op if a child is selected, but can I disable its selection?

_____________________________________________________
Believe! Every thing has a purpose

Re: Ok One more question people

Heath Stewart30-Jun-04 6:02

Heath Stewart

30-Jun-04 6:02

You can cancel the selection of a node by handling the TreeView.BeforeSelect event:

treeView1.BeforeSelect +=
  new TreeViewCancelEventHandler(treeView1_BeforeSelect);
// ...
private void treeView1_BeforeSelect(object sender,
  TreeViewCancelEventArgs e)
{
 if (e.Node.Nodes.Count > 0) e.Cancel = true;
}

If you want to have more control over what people can add, this is where encapsulation comes in. Rather than trying to hack the TreeView to allow/disallow certain operations, host the TreeView in a UserControl or something where you define methods and properties that reflect operations in the TreeView. This way you can easily perform a check before doing something, like how many nodes exist and whether you should add a new one. To implement this kind of behavior on the tree can be quite difficult. This is the reason for encapsulation.

Microsoft MVP, Visual C#
My Articles

Re: Ok One more question people

saud_a_k30-Jun-04 19:10

saud_a_k

30-Jun-04 19:10

ok..
I'll try this.. thank you.

_____________________________________________________
Believe! Every thing has a purpose

GPS data via Bluetooth (com port communication)

stanlyB2329-Jun-04 12:18

stanlyB23

29-Jun-04 12:18

Hello,

I'm having a problem to read data from my bluetooth gps mouse!
In detail: I'm trying to program a little tool for an IPaq 5450 PPC 2003 which reads the gps data that comes in from the virtual com port (in my case com port 8). That is where my problem begins. I'm pretty new with c# and serial port communication at all! So i hope anyone of you can help me with that problem! How do i open the serial com port in c# and start reading out of a buffer!
I just need the simple geographical coordinates. Not more!
And please no recommendation to use another language... i have to use c#, because it's part of a bigger project!

hope someone can help me...

nils

Re: GPS data via Bluetooth (com port communication)

Heath Stewart29-Jun-04 13:59

Heath Stewart

29-Jun-04 13:59

.NET 1.x does not include a serial stream reader/writer class; .NET 2.0 will (finally). There are several classes available that people have written to get around this problem. If you try the following search, you'll find several hits:

http://www.codeproject.com/info/search.asp?cats=3&cats=5&searchkw=serial+com+port[^]

As far as using another language (because you're easiest way to talk to a serial port is using Managed C++), you do realize that you can write assemblies using any managed language, don't you? You could, for example, write an assembly in Managed C++ (typical when many native functions and supporting data types need to be used) and reference that in your C# project just like you reference System.dll, System.Data.dll, etc. The .NET BCL assemblies are written in C# yet they're used by all other managed languages (MC++, VB.NET, Perl.NET, COBOL.NET, etc.).

Use what makes it the easiest.

If you want additional help for reading NMEA data from your GPS unit, try the following google search:

http://www.google.com/search?q=GPS+C%23[^]

There are many great examples and even some third-party libraries which could do all this for you.

Microsoft MVP, Visual C#
My Articles

Re: GPS data via Bluetooth (com port communication)

pxp29-Jun-04 21:57

pxp

29-Jun-04 21:57

Have a look at GPS Reader NMEA 0-183[^]

He uses a DBComm dll.

Also nice way of showing sat's on screen.

Good starting point,...

Re: GPS data via Bluetooth (com port communication)

stanlyB2329-Jun-04 23:50

stanlyB23

29-Jun-04 23:50

well, looks like what i'm looking for! but do i need to write the dbcomm.dll on my own or can i download it somewhere. so far i wasn't able to find it!

nils

Re: GPS data via Bluetooth (com port communication)

pxp30-Jun-04 0:01

pxp

30-Jun-04 0:01

look at www.gotdotnet.com[^]

Encryption problems

Not Active29-Jun-04 10:25

Not Active

29-Jun-04 10:25

I'm using this code (from a MS example) to encrypt/decrypt simple strings. These methods work fine while I maintain an instance of the class but if I encrypt a string, then later want to decrypt it (using the same key of course)
the first 5 characters or so are messed up.

<br />
		public string EncryptString(string strValue)<br />
		{<br />
			SymmetricAlgorithm m_csp = new TripleDESCryptoServiceProvider();<br />
			ICryptoTransform ct = m_csp.CreateEncryptor(m_csp.Key, m_csp.IV);<br />
			byte[] byteBuf = Encoding.UTF8.GetBytes(strValue.PadLeft(5, '*'));<br />
			MemoryStream ms = new MemoryStream();<br />
			CryptoStream cs = new CryptoStream(ms, ct, CryptoStreamMode.Write);<br />
			cs.Write(byteBuf, 0, byteBuf.Length);<br />
			cs.FlushFinalBlock();<br />
			cs.Close();<br />
<br />
			return Convert.ToBase64String(ms.ToArray());<br />
		}<br />
<br />
		public string DecryptString(string strValue)<br />
		{<br />
			SymmetricAlgorithm m_csp = new TripleDESCryptoServiceProvider();<br />
			ICryptoTransform ct = m_csp.CreateDecryptor(m_csp.Key, m_csp.IV);<br />
			byte[] byteBuf = Convert.FromBase64String(strValue.Trim());<br />
			MemoryStream ms = new MemoryStream();<br />
			CryptoStream cs = new CryptoStream(ms, ct, CryptoStreamMode.Write);<br />
			cs.Write(byteBuf, 0, byteBuf.Length);<br />
			cs.FlushFinalBlock();<br />
			cs.Close();<br />
<br />
			return Encoding.UTF8.GetString(ms.ToArray());<br />
		}<br />
<br />

Re: Encryption problems

Heath Stewart29-Jun-04 14:11

Heath Stewart

29-Jun-04 14:11

Something obviously is stored in that class that you're not saving (perhaps the key, which in these snippets is getting created each time, even between encryption and decryption calls).

How are you saving the ciphertext across calls and instances of the containing class? Are you writing them to a file? If you use a TextWriter, you may be inadvertently writing a BOM (byte order mark) to the beginning of the file. Depending on how you read the file back in, this BOM may become part of the ciphertext (a TextReader should strip this, but if you use a FileStream or something, it won't be stripped from the rest of the ciphertext, for example).

The only thing with block ciphers is, though, that if something is screwed up then the ciphertext would be invalid. The only possibility for this not to happen as I see it is if a particular block of ciphertext were changed and the block data size wasn't changed, and this may only work (depending on the algorithm) if the data wasn't signed, either (because the digest would be invalid). If this is possible (depending on the algorithm), then the rest of the blocks should decrypt.

Microsoft MVP, Visual C#
My Articles

Re: Encryption problems

Not Active29-Jun-04 16:16

Not Active

29-Jun-04 16:16

Thanks Heath, I found the error. The key being used was the same for encryption and decryption but I was generating the initalization vector each time ( GenerateIV() ). After I made sure to use the same for each way it works fine. Doh!!

Cystal Report Chart questions-C# Winforms using cystal report

Anonymous29-Jun-04 9:40

Anonymous

29-Jun-04 9:40

1.Is there anyway, when selecting a chart in a report, to have it enlarged on the next page automatically such as 150% bigger?

2. The Y axis of the graph gets cut off if it has a too large number.(start from Zero). How to enlarge the margin to show the whole number? And how can I put a number starts from ( if not from Zero) and how can I define an increment step by my own?

3.To show a summary of a report field in a chart, it will show 'Sum of TableName.FieldName' Format in the legent. I want to customize a name for the summary such as 'Total Sales' instead of ' Sum of SalesTable.SalesPerMonth ',
I have tried to define a custom field to hold the summary resault, but the chart is showing @TotalSale. with '@' in legent.
How can I customize a name for the legend?

Thanks in advance.

C# missing anonymous classes?

vista2729-Jun-04 8:39

vista27

29-Jun-04 8:39

so i finally came across a situation today that i thought would be ideal if i were able to implement an anonymous class on the fly like you can in java. by default, ComboBoxes use the ToString() method as the listed label when you add an item to it. So if you create a new object, add it to the comboBox, it will be listed as a "System.Object". What I wanted to do was to simply add an object for only one purpose, to list itself as "ALL". So I created a class just so I can override the ToString() to return "ALL" and passed it into the Items.Add(). it would have been nice to do it like in java like so:

ComboBox.Items.Add(new object(){
public override string ToString(){
return "ALL";
}
})

but u can't do that in C#. Smile | :)

any comments?

Re: C# missing anonymous classes?

Judah Gabriel Himango29-Jun-04 8:49

Judah Gabriel Himango

29-Jun-04 8:49

Unless I'm misunderstanding, C# provides a much more elegant way to do this:

ComboBox.Items.Add("ALL");

#include "witty_sig.h"

Re: C# missing anonymous classes?

vista2729-Jun-04 9:22

vista27

29-Jun-04 9:22

haha, OK, i agree, your way is a tad more elegant.

but ok, for the sake of argument, what IF there were no overloaded version that took a string argument, and internally the ony way to make the display change was to alter the ToString() method. and maybe you want to add a few things to the class and don't need to save references to the objects. THEN wouldn't it be nice to have anonymouse classes? Smile | :)

Re: C# missing anonymous classes?

Judah Gabriel Himango29-Jun-04 9:45

Judah Gabriel Himango

29-Jun-04 9:45

Actually it's not an overloaded method. All types in the .NET BCL (pointers aside) inherit from System.Object. Since a the listbox wants an object, you can pass literally anything into it, an int, string, bool, whatever.

Now as for anonymous classes, the case you're making for is anonymous objects. To me I don't see a real need; you're defining and instanciating an object in place -- if you really need to instanciate with custom data just use a regular class; less clutter and more concise code that way IMO. But maybe that's just me. Smile | :)

#include "witty_sig.h"

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.