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Hello all 
I have this problem with managing resources. I am writing a cataloging application in which i need to compute a MD5 hash value for each file in the tree structure given a directory. This is done recursively. Now until I have added a function to compute the hash everything was working smoothely however now the application freezes.
This could be because i do not have enough free resources. I tried calling a Dispose method of the MD5CryptoServiceProvier but it is protected therefore not allowed to be accessed.
IS Garbage Collector an option? If so where should it be applied.
To give you an idea. The function ComputeHash looks the following:
private string ComputeDigest(FileInfo file)<br />
{ <br />
MD5CryptoServiceProvider csp = new MD5CryptoServiceProvider();<br />
FileStream fstream;<br />
try<br />
{<br />
fstream = File.OpenRead(file.FullName);<br />
}<br />
catch(Exception e)<br />
{<br />
MessageBox.Show("Error Occured: " + e.Message);<br />
return null;<br />
}<br />
byte [] hash = csp.ComputeHash(fstream);<br />
fstream.Close();<br />
string hash_string = String.Copy(BitConverter.ToString(hash));<br />
csp.Clear();<br />
return hash_string;<br />
}
Izabela
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Im building a C# wrapper for an unmanaged dll (BladeEnc.dll) and im not an expert in this, anyways.
I need to pass the following struct in:
BE_ERR beInitStream( PBE_CONFIG pbeConfig, PDWORD dwSamples, PDWORD dwBufferSize, PHBE_STREAM phbeStream )
typedef struct {
DWORD dwConfig;
union {
struct {
DWORD dwSampleRate;
BYTE byMode;
WORD wBitrate;
BOOL bPrivate;
BOOL bCRC;
BOOL bCopyright;
BOOL bOriginal;
} mp3;
struct {
DWORD dwSampleRate;
BYTE byMode;
WORD wBitrate;
BYTE byEncodingMethod;
} aac;
} format;
} BE_CONFIG, *PBE_CONFIG;
Now i got this in C#:
[StructLayout(LayoutKind.Sequential, Pack = 1)]
internal struct BE_CONFIG
{
public Int32 dwConfig;
public sFormat format;
}
[StructLayout(LayoutKind.Sequential)]
public struct sFormat
{
public sMP3 mp3;
public sAAC aac;
}
[StructLayout(LayoutKind.Sequential)]
public struct sMP3
{
public Int32 dwSampleRate;
public byte byMode;
public Int16 wBitrate;
public bool bPrivate;
public bool bCRC;
public bool bCopyright;
public bool bOriginal;
}
[StructLayout(LayoutKind.Sequential)]
public struct sAAC
{
public Int32 dwSampleRate;
public byte byMode;
public Int16 wBitrate;
public byte byEncodingMethod;
}
Now im testing this function (beInitStream) with the following code:
BE_CONFIG config;
Int32 dwSamples = 0;
Int32 dwBufferSize = 0;
int output;
IntPtr pConfig = IntPtr.Zero;
FileStream fs = new FileStream("C:\\test.mp3", FileMode.Create, FileAccess.Write);
config.dwConfig = BE_CONFIG_MP3;
config.format.mp3.dwSampleRate = 44100;
config.format.mp3.byMode = BE_MP3_MODE_STEREO;
config.format.mp3.bPrivate = false;
config.format.mp3.bCRC = false;
config.format.mp3.bCopyright = false;
config.format.mp3.bOriginal = false;
Marshal.StructureToPtr(Marshal.SizeOf(config), Marshal.AllocHGlobal(pConfig), false);
output = beInitStream(ref pConfig, ref dwSamples, ref dwBufferSize, fs.Handle);
Marshal.FreeHGlobal(pConfig);
fs.Close();
I keep getting the error BE_ERR_INVALID_FORMAT_PARAMETERS, so im assuming that there is something wrong with the structure.
Could anyone confirm and/or help me with this?
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hi
i want to draw lines and pictures in datagrid headers
does any one can help me ..?
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I am not sure about drawing picture in Datagrid Header. But i wrote an article on Datagrid Formatting which will do text formattings. Please refer that article for more information.
Sreejith Nair
[ My Articles ]
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How do I send a string to the printer when I click on a specific button? And how do I add a CR (carriage return) into a string?
Mike
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Michael Williams wrote:
How do I send a string to the printer when I click on a specific button?
Printing is a complex topic (simplified by Windows Forms and .NET, but still complex). Even to print a single string, you need to create a PrintDocument object, and install handlers for various events. See MSDN documentation.
Michael Williams wrote:
And how do I add a CR (carriage return) into a string?
That's easier. Just concatenate a "\n". That should work, but in some cases, you'll need the full CRLF: "\n\r".
strLines = strLine1 + "\n" + strLine2; -- LuisR
Luis Alonso Ramos
Intelectix - Chihuahua, Mexico
Not much here: My CP Blog!
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Printing in .NET is not that much tough as i know. Please refer this article to get to know about more.
Printing in C#
Sreejith Nair
[ My Articles ]
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I need to read up on the implication of server farm AND database clustering on COM+ transaction. Any reference? Preferably URL's so I don't need to rush off to the bookstore.
Thanks in advance.
Norman Fung
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I'n new to programming and I'm writing a simple app where I generate a 2 digit random number in one textbox. When I click a button, I want the value of that textbox to appear inside another textbox.
After playing with this for hours (and learning along the way), I'm getting nowhere.... The closest I've come is this;
textBox1a.Text = (textBox1.ToString());
The text is entered into the text box as follows:
System.Windows.Forms.TextBox, Text: xx (where xx is the random #)
I don't want this - I just want the random number in place and not the whole string.
Any suggestions?
Thanks,
Mike
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I recommand you to study or refer few C# programming books. MSDN is a nice guide for newbee like you. Better don't get into Visual Studio.NET IDE untile and unless you know little about how to use .NET laguages.
Here is the solution for your issue.
textBox1a.Text = (textBox1.Text.ToString());
Sreejith Nair
[ My Articles ]
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sreejith ss nair wrote:
MSDN is a nice guide for newbee like you.
MSDN has a lot of useful information for anyone programming with Microsoft technologies. (I'll assume the condescending tone was unintentional.)
sreejith ss nair wrote:
Better don't get into Visual Studio.NET IDE untile and unless you know little about how to use .NET laguages.
I think that is bad advice. Read all you can, yes, but do it in addition to coding, not instead of it.
Charlie
if(!curlies){ return; }
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sreejith ss nair wrote:
textBox1a.Text = (textBox1.Text.ToString());
Why, again, are you using .ToString() on a string???
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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There are no default properties in C#, so you'll need to specifically state what property of textBox1 you're trying to get at, which, in this case, is the Text property.
textBox1a.Text = textBox1.Text; The compiler can't infer what you meant because you could have just as easily wanted to display textBox1's Name, BackColor, or PasswordChar, etc., in textBox1a.
Charlie
if(!curlies){ return; }
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Thanks for the help. The first reply solved my problem. I agree that I should be reading AND doing to learn the mosr efficient way. Thanks Charlie!
I have another ? that I'll post in a new thread.
Mike
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Any suggested reading on Class's, Inheritance and class accessbility with C#?.. I'm getting my feet wet with ClassLibraries and been finding nothing but too abstract examples from .NET's help.. want to protect what can be instantiated w/out nesting class's.. trying to funnel creation thru single class. I'm sure its the bee's and not the bears in this neck of the woods but if anybody's found any good examples plz let me know..
aspiringCodeMonkey says ...
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You Wrote : Any suggested reading on Class's, Inheritance and class accessbility with C#?
In .NET we have different class types. Say Abstract class, Selaled class , Concreate Class , Singleton class etc.
In .NET we have classical(is a) inheritance and containmnet(has a).
In .NET we have different type of access modifiers. Say Public,private,Protected,Internal,Internal Protected.
So it is very tough to explain entire concept in a small paragraph. And also it is very tough to see your requirement in one article (consolidated). So what i suggest you is search and find few article related to above mentioned keywords.
This will also help you to learn about Class Libraries
Getting Started With Class Lib
Sreejith Nair
[ My Articles ]
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The immediate answer to your problem is to specify any classes that you only want visible within the class library as 'internal', and have one 'public' class, which is accessible to anything referencing your library. However, internal classes are completely invisible outside the class library.
Another trick is to make a class public, but make all its constructors internal, so it can only be created by other classes in the same library, but can then used by any code anywhere.
Hope that helps,
Andrew
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How can I divide Application to FRAMES so that I can display Forms to these Frames ?
Who know please help me.
Thanks alot
change global
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Search MSDN for the documentation for the Splitter class. It allows you to divide a form into frames.
-- LuisR
Luis Alonso Ramos
Intelectix - Chihuahua, Mexico
Not much here: My CP Blog!
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I have a control that includes a few buttons, a drop down and a text box.
There is a property called DestinationGrid which is set at design time to be the grid the control works with. I also have another property called SelectedRow which is used to set the on the grid. Because the grid doesnt have any rows I get an error when I view the form at design time saying that SelectedRow - Object not set to an instance ...
How can I stop thsi error occuring?
I could remove the property and use a SetSelectedRow() and GetSelectedRow() method, but would like to use a property.
Any suggestions? Thanks
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Write a intialiser in your custom class constructor. That means, in your custom control constructor you have to initalise the selected row value if the datagrid is selectable. To check whether datagrid is selectable use this dataGrid1.CanSelect property . If it is selectable then it will return true else will return false.
This is only a small idea to handle the situation.
Sreejith Nair
[ My Articles ]
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Here is my problem. I have a vb.net form that is an FTP client, It calls a C# class for when it downloads a file. while the file is being downloaded it is in a loop in the C# class.
Info on the vb.net form dosnt get updated until the download finishes and C# class exits the loop.
how do I make the C# class update the form with download stats while sill in the loop? I need this to be able to show download speed and progress.
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Why don't you create a thread from which you call the C# class.
Then Loop while waiting for the thread to complete, and update the form while in the loop?
Pauwll
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how would i do that?
right now its somthing like this.
progress1.progress = 0
ftp.Download(filename)
statusbar.panels(0).text = "Done Downloading"
once it gets to the download line it starts donwloading and the program seems like its frozen until the download finishes, then it continues like normal.
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This is because your Userinterface and Download are in the same thread, as mentioned before. A thread is linear, meaning in order to execute order 3, you need to do 1 and 2 first.
This means, if you have a thread which loops from 1 to 10 and prints, the result will be:
1
2
3
4
5
6
7
8
9
10
Your program is busy with the Download code, so it cannot execute the UI-code at the same time.
What you need to read about is "multithreading", e.g. have your computer do several things at the same time.
If you had 2 threads looping from 1 to 10, you could get:
1
1
2
3
2
4
3
5
4
5
6
6
7
7
8
9
8
10
9
10
This is because Windows decides which thread gets to execute at any time, but tries to divide processing time evenly among threads (this changes if you start messing with priorities).
Fire up MSDN (online or local) and read up on the System.Threading namespace.
If you have a static method you want to run in its own thread, just
create a new thread (Thread oThread = new Thread(new ThreadStart(myStaticMethod));) and then start this thread (oThread.Start();).
It will automatically stop after it has completed its work.
You could also use QueueUserWorkItem if you want Windows to take care of creating and starting your thread, or you could use asynchronous methods for your FTPing.
Cheers
Sebs
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