Help! Got big picture wrong...

[kaiser]

I have been trying to write a program that monitors a text file, and if
the last value in the text file changes (ie : the file is updated), the
program does a series of events.

Thus far, with A LOT of forum help, I have created a program that
continiously loops through the file until the last line is found, and
will do that until the user stops the process by clicking a button.

The problem is that once the program is running, ANOTHER program might
try to access it and change the value...when I run the first program
that reads and detects a change the second program, for now a simple
..txt writer, bombs out because (I assume) the file cant be opened
twice.

Does anyone know how to get around this issue?

while (ContinueLoop == true )
{
while ((line) != null)
{
LastLine = line;
line = file.ReadLine();
}

lblCounter.Text = Counter.ToString();
lblString.Refresh();
lblCounter.Refresh();
Application.DoEvents();
Counter++;
lblString.Text = LastLine;
file.BaseStream.Seek(0,System.IO.SeekOrigin.Begin) ;
line = "not null";
} // While do until button pressed

[Bruno Jouhier]

You have to specify a special sharing mode when you open a file. Take a look
at the FileShare enum in the doc.

Also, as it is written below, your program will eat 100% CPU and slow down
all other apps when there is nothing to read. You should use the
FileSystemWatcher API to detect when the file changes instead of calling
ReadLine in a loop.

Bruno

"kaiser" <mi*****@cactusblue.com> a écrit dans le message de news:
11**********************@g47g2000cwa.googlegroups. com...

I have been trying to write a program that monitors a text file, and if
the last value in the text file changes (ie : the file is updated), the
program does a series of events.

Thus far, with A LOT of forum help, I have created a program that
continiously loops through the file until the last line is found, and
will do that until the user stops the process by clicking a button.

The problem is that once the program is running, ANOTHER program might
try to access it and change the value...when I run the first program
that reads and detects a change the second program, for now a simple
.txt writer, bombs out because (I assume) the file cant be opened
twice.

Does anyone know how to get around this issue?

while (ContinueLoop == true )
{
while ((line) != null)
{
LastLine = line;
line = file.ReadLine();
}

lblCounter.Text = Counter.ToString();
lblString.Refresh();
lblCounter.Refresh();
Application.DoEvents();
Counter++;
lblString.Text = LastLine;
file.BaseStream.Seek(0,System.IO.SeekOrigin.Begin) ;
line = "not null";
} // While do until button pressed

[Bob Powell [MVP]]

It sounds to me like you need to be using the file system watcher to monitor
this text file. You can just react to the notification of change and then go
to the end of the file without all that looping through stuff which seems
tome to be nothing more than a way to eat up processor cycles.

--
Bob Powell [MVP]
Visual C#, System.Drawing

Ramuseco Limited .NET consulting
http://www.ramuseco.com

Find great Windows Forms articles in Windows Forms Tips and Tricks
http://www.bobpowell.net/tipstricks.htm

Answer those GDI+ questions with the GDI+ FAQ
http://www.bobpowell.net/faqmain.htm

All new articles provide code in C# and VB.NET.
Subscribe to the RSS feeds provided and never miss a new article.

"kaiser" <mi*****@cactusblue.com> wrote in message
news:11**********************@g47g2000cwa.googlegr oups.com...

I have been trying to write a program that monitors a text file, and if
the last value in the text file changes (ie : the file is updated), the
program does a series of events.

Thus far, with A LOT of forum help, I have created a program that
continiously loops through the file until the last line is found, and
will do that until the user stops the process by clicking a button.

The problem is that once the program is running, ANOTHER program might
try to access it and change the value...when I run the first program
that reads and detects a change the second program, for now a simple
.txt writer, bombs out because (I assume) the file cant be opened
twice.

Does anyone know how to get around this issue?

while (ContinueLoop == true )
{
while ((line) != null)
{
LastLine = line;
line = file.ReadLine();
}

lblCounter.Text = Counter.ToString();
lblString.Refresh();
lblCounter.Refresh();
Application.DoEvents();
Counter++;
lblString.Text = LastLine;
file.BaseStream.Seek(0,System.IO.SeekOrigin.Begin) ;
line = "not null";
} // While do until button pressed