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Hello everyone! My first post here 
As you might have guessed from the message title: is it possible to read from a text file, while another application is always writing to it, without disturbing the writing process? And if it is, how do I do it?
I'd like to create an application that open such a file, and gets the data that has been added to the file since my last read (maybe you've got some good suggestions how to do that?).
Thanks in advance,
Paul
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It might be possible to read from the file, but it's hard to guarantee that it would never disturb the writing process.
It sounds like you should use something that has much better functionality to handle multiple users, like a database.
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b { font-weight: normal; }
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That is true, but my question was more out of curiosity after observing programs like AviPreview or VLAN play avi or mpg files while they were still being downloaded. I hope someone knows a solution because this is driving me nuts 
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pistolenpaultje wrote: AviPreview or VLAN play avi or mpg files while they were still being downloaded
I don't know about these programs but it looks like LimeWire just pauses the download while it writes the downloaded bits so far to a temporary file which it then displays. Maybe these programs do the same and you havn't realised.
You know you're a Land Rover owner when the best route from point A to point B is through the mud.
Ed
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Are you talking about something similar to the Unix tail command? If so, you might just want to look at something like this[^].
--
I've killed again, haven't I?
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i looked at that, but it waits until the writing process is complete and then opens the file and reads the changes. i'd like to know how to read a file that is being written to while it happens. Or, probably the same, an application that is writing to the file sporadically but never closes the file handle while it is running.
thank you for your reply though, i'll get there!
maybe this is good material for an article: Advanced File I/O 
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I'm not sure how helpful this is, but I accidentally did something like that a while back. I wrote a program that was supposed to start capturing the screen into a WMV. I made the mistake of telling it to start capturing when it lost focus, as well as play the captured file when I manually stopped it. The result was this:
- captured WMV (wrote file)
- played WMV in MediaPlayer
- program lost focus
- program started writing to same WMV just before MP started playing it
- I saw the multiple smaller-and-smaller time-delayed MediaPlayer windows in the video.
Basically, MediaPlayer was reading a file that was being written just a little ahead of it, so I know it's POSSIBLE. It's just a matter of fooling Windows into doing it intentionally.
-Daniel
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That's exactly what i mean! Funny though, because I never caught WMP doing anything like that (it refuses to play avi's or mpg's while the download is still in progress). Maybe it's because WMV's are designed with streaming in mind, so WMP opens it differently than avi's or mpg's..
Paul
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I'm not very knowledgeable about streaming or deep file IO junk, but it would make sense for WMP to check to see if the file is not currently being written to.
In my scenario, I wouldn't be surprised if my program hadn't quite started writing to the file when WMP checked it (the WMV was a distinct file from a previous start-stop capture), kind of like how people used to play copied PS games (I never did, but I heard how to do it, with a real disk when the PS does its little preliminary validity check, then swapping).
-Daniel
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you just have to keep tracks of the position of the writing process and limit yourself to not read beyond where the last write position was.
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sounds like just what i need! however i already tried something like that but couldn't get it to work. do you have any suggestion (maybe an article link or code snippet) how i could accomplish that? many thanks for your reply, i now have an idea in what direction to search!
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Does the C# Express Edition include the ability to deploy the application? I have seen that VS2005 has ClickOnce, but I cannot determine if it is available in Express Edition.
Also, are there any other options besides InstallShield to deploy VS2005 applications?
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econner wrote: Does the C# Express Edition include the ability to deploy the application? I have seen that VS2005 has ClickOnce, but I cannot determine if it is available in Express Edition.
Does this answer your question.
econner wrote: Also, are there any other options besides InstallShield to deploy VS2005 applications?
NSIS, InnoSetup. I personally don't bother with InstallShield, MSI or ClickOnce. It's just this feeling of being in complete and utter control of NSIS that gives me a warm feeling
I suggest you take a look at the installer script for Sharpdevelop if you want a good example of installing .NET applications using NSIS. The #develop script performs checks for frameworks, registers file associations, custom bitmaps etc etc.
You've probably guessed this by now but I'd strongly recommend NSIS, the things you can do with it are endless. I even wrote scripts which would install mods into GTA III, Vice City and San Andreas with it  .
You know you're a Land Rover owner when the best route from point A to point B is through the mud.
Ed
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Thanks.
I will take a look at NSIS.
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Good man
I might warn you that although you have complete control overall, sometimes you do want a quick drag & drop solution, there are multiple NSIS editors out there (look on the Wiki) and some even have wizards. But if you use it regularly then there's nothing stopping you (hopefully).
You know you're a Land Rover owner when the best route from point A to point B is through the mud.
Ed
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I have taken a "quick" look already this evening. Looks very good. I believe I seen where it does also support the installation of the .NET framework if needed. I will take a closer look in the next day or so.
Thanks again.
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Hi,i'm trying to make a round edjed form with gdi+, it works pretty good when you do it in a normal form, but has a midiparent(a form inside the mdicontainer) the colorthat is drawn is the one that is suposed to be the transparencykey.
in the code that criates the round edjed form i pus:
childform.allowtransparency = true;
does anyone have an idea of how to draw something tranparent?
thanks for everything :P
_________________________________________________________________________________
"There is no great genius without some touch of madness." - Seneca (5 BC - 65 AD)
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i am developing a project on outgoing call. i want to play an audio file when the phone is connected. i have used the following code:
ITTerminalSupport ts = (TAPI3Lib.ITTerminalSupport)ia[0];
string str=TAPI3Lib.TapiConstants.CLSID_String_FilePlaybackTerminal;
//MessageBox.Show(str);
int k= TAPI3Lib.TapiConstants.TAPIMEDIATYPE_MULTITRACK;
//MessageBox.Show(k.ToString());
ITTerminal fpbt =
ts.CreateTerminal(str,k, TAPI3Lib.TERMINAL_DIRECTION.TD_CAPTURE);
ITMediaPlayback mp =(TAPI3Lib.ITMediaPlayback)fpbt;
object[] audiofile=new object[1];
audiofile[0]=@"C:\Documents and Settings\Ankita\Desktop\project\tapi3_dev\tapi3_dev\my 3rd file.wav";
mp.PlayList=audiofile;//because it requires objet array.
/*If you have already selected terminal by bcc.SelectTerminalOnCall(terminal)
then please unselect it by bcc.UnselectTerminalOnCall(terminal)*/
//bcc1.SelectTerminalOnCall(fpbt);
mc=(TAPI3Lib.ITMediaControl)fpbt;
try
{
mc.Start();//will start playing the audiofile.
}
catch(Exception exp)
{
MessageBox.Show(exp.Message.ToString());
}
the code runs successfully but without playing an audio file even though the file is in correct format.
can anyone help me. i am using a voice modem.
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Hi ALL
I want to make my application receives events from the system that a specific process has been started or ended
how to do this
Thx all
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Hello,
I'm using a third party COM dll, which I've referenced in my C# project. However, when I call a certain function in it, it throws an error message saying "The instruction at 0x10153c89 referenced memory at 0x0751629c. The memory could not be 'read'" and then the application terminates.
Is this most likely to be an error in the COM dll, or does anyone else have any other ideas on what the problem may be?
When Visual Studio generates the interop assembly for the COM dll and places it in your build output directory, how does it 'route' the function calls to the actual COM dll it wraps, or is this information contained within the interop assembly itself?
Thanks for your time and help
Shehzad
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cheeze103 wrote: When Visual Studio generates the interop assembly for the COM dll and places it in your build output directory, how does it 'route' the function calls to the actual COM dll it wraps, or is this information contained within the interop assembly itself?
The COM interop assembly contains the globally unique identifier (GUID) of COM object it's calling. The CLR will marshal the data between managed and unmanaged appropriately (sometimes with hints from code, such as the MarshalAsAttribute).
As far as the error, there's no way that we can know. Can you show us the function signature (both native COM and .NET wrapper) for that function that's causing the error?
Tech, life, family, faith: Give me a visit.
I'm currently blogging about: Is Jesus the Jewish Messiah?
The apostle Paul, modernly speaking: Epistles of Paul
Judah Himango
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| blockquote class="FQ"> Judah Himango wrote: As far as the error, there's no way that we can know. Can you show us the function signature (both native COM and .NET wrapper) for that function that's causing the error?
Sure:
in 'original COM dll' (shown in VB6):
<br />
Public Sub ConnectProjectEx(_ByVal DomainName As String,_ByVal ProjectName As String,_ByVal UserName As String,_ByVal UserName As String,_Optional ByVal Password As String = " "_)<br />
and in the interop wrapper (using ildasm):
<br />
.method public hidebysig newslot virtual <br />
instance void ConnectProjectEx([in] string marshal( bstr) DomainName,<br />
[in] string marshal( bstr) ProjectName,<br />
[in] string marshal( bstr) UserName,<br />
[in][opt] string marshal( bstr) Password) runtime managed internalcall<br />
When I pass to this function an invalid username or password, it actually throws an exception, saying 'The user so and so does not exist'. However, when I give it a correct user, it throws the application error I mentioned before - it seems that it gets further in the dll function, and then fails, and since I can't see the actual code in the COM dll (since it's third party), I don't know what to do!
Thanks for your help.
Shehzad
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Hi,
I have developped no more Winforms applications since quite long.
I can't see how to create "global variables or objects" that would be shared among all the winforms?
In the webforms I was used to Session variables, but with winforms..? Any clue to do the same? Or in message driven way?
Any help is welcome.
Thanks a lot.
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You could make your "global" variables members of a singleton Globals class that's accessible by all the forms in your application.
/ravi
My new year's resolution: 2048 x 1536
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