While Loop with a StreamReader process included for fun

  • Thread starter Thread starter William Foster
  • Start date Start date
W

William Foster

Good evening all,

I am trying to write a process that uses a while loop to cycle multiple
files from an array throught the StreamReader Process.

The whole thing works using:

Dim Import_File_Reader As System.IO.StreamReader

While ...
Import_File_Reader = New StreamReader(Import_File_and_Path)
.... Extract all the data I want then start again ....
End While

However, when I get to the second run through it always return an error
saying that there was an illegal character included in the
Import_File_and_Path variable; on checking there are no illegal characters.
All I can think is that without closing off the Import_File_Reader variable
before running through the While loop for a second time it will not work,
however, when I add in Import_File_Reader.Close towards the bottom of the
While Loop it still doesn't work [The same error is returned].

I am a bit lost know, if anyone has any ideas on how to get this to work it
would be greatly appreciated if you could respond to this query as I am left
with the option of opening every file seperately through different variables
if this doesn't work; and with over 700 files to be opened I am not liking
that option.

Yours sincerely,

William Foster
 
Hi,
Try below code which will help you atleast know exact problem:
// show error if user specified invalid file
if ( fileName == "" || fileName == null )
MessageBox.Show( "Invalid File Name", "Error",
MessageBoxButtons.OK, MessageBoxIcon.Error );
else
{
// create FileStream to obtain read access to file
input = new FileStream( fileName, FileMode.Open,
FileAccess.Read );

// set file from where data is read
fileReader = new StreamReader( input );
}
As We pass constant FileMode.Open as the second argument to the FileStream
constructor to indicate that the FileStream should open the file if it exists
or should throw a FileNotFoundException if the file does not exist
 
Manish,

Thanks for the help, however, I have already confirmed the file name are
correct and don't contain any errors. I have used the internal function to
automatically load an array with files within a directory that meet a certain
criteria.

I think the error being returned has nothing to do with the actual error.

If you have any further thoughts let me know.

Yours sincerely,

William Foster


Manish Bafna said:
Hi,
Try below code which will help you atleast know exact problem:
// show error if user specified invalid file
if ( fileName == "" || fileName == null )
MessageBox.Show( "Invalid File Name", "Error",
MessageBoxButtons.OK, MessageBoxIcon.Error );
else
{
// create FileStream to obtain read access to file
input = new FileStream( fileName, FileMode.Open,
FileAccess.Read );

// set file from where data is read
fileReader = new StreamReader( input );
}
As We pass constant FileMode.Open as the second argument to the FileStream
constructor to indicate that the FileStream should open the file if it exists
or should throw a FileNotFoundException if the file does not exist



--
Hope this helps.
Thanks and Regards.
Manish Bafna.
MCP and MCTS.



William Foster said:
Good evening all,

I am trying to write a process that uses a while loop to cycle multiple
files from an array throught the StreamReader Process.

The whole thing works using:

Dim Import_File_Reader As System.IO.StreamReader

While ...
Import_File_Reader = New StreamReader(Import_File_and_Path)
.... Extract all the data I want then start again ....
End While

However, when I get to the second run through it always return an error
saying that there was an illegal character included in the
Import_File_and_Path variable; on checking there are no illegal characters.
All I can think is that without closing off the Import_File_Reader variable
before running through the While loop for a second time it will not work,
however, when I add in Import_File_Reader.Close towards the bottom of the
While Loop it still doesn't work [The same error is returned].

I am a bit lost know, if anyone has any ideas on how to get this to work it
would be greatly appreciated if you could respond to this query as I am left
with the option of opening every file seperately through different variables
if this doesn't work; and with over 700 files to be opened I am not liking
that option.

Yours sincerely,

William Foster
Click to expand...
Click to expand...
 
You are currently dimming a single streamreader, not initializing it, and
then initializing it over and over in your loop.

There might be a better way of doing this and it actually confirms that the
object is destroyed. That is by using the "Using" clause. The "Using" clause
makes sure the object is completely destroyed outside the Using range.

Example:

While . . .
'Insert code to populate sFilePath
Using Import_File_Reader as New System.IO.StreamReader(sFilePath)
... Extract data from file. etc
'No need to destroy the file reader it is automatically destroyed by
the engine.
End Using
End While

Let me know if that helps. Good luck.
 
Mohamad,

Thanks for your assistance, on the good side your recommendation has
certainly improved my coding. On the bad side it did not resolve my error;
on further investigation [painful investigation] I found that I had misplaced
a vbCr within a seperate process which was coming into causing the error.

Thanks for your help!

William Foster

Mohamad Elarabi said:
You are currently dimming a single streamreader, not initializing it, and
then initializing it over and over in your loop.

There might be a better way of doing this and it actually confirms that the
object is destroyed. That is by using the "Using" clause. The "Using" clause
makes sure the object is completely destroyed outside the Using range.

Example:

While . . .
'Insert code to populate sFilePath
Using Import_File_Reader as New System.IO.StreamReader(sFilePath)
... Extract data from file. etc
'No need to destroy the file reader it is automatically destroyed by
the engine.
End Using
End While

Let me know if that helps. Good luck.

--
Mohamad Elarabi
Lead Developer. MCTS, MCPD.


William Foster said:
Good evening all,

I am trying to write a process that uses a while loop to cycle multiple
files from an array throught the StreamReader Process.

The whole thing works using:

Dim Import_File_Reader As System.IO.StreamReader

While ...
Import_File_Reader = New StreamReader(Import_File_and_Path)
.... Extract all the data I want then start again ....
End While

However, when I get to the second run through it always return an error
saying that there was an illegal character included in the
Import_File_and_Path variable; on checking there are no illegal characters.
All I can think is that without closing off the Import_File_Reader variable
before running through the While loop for a second time it will not work,
however, when I add in Import_File_Reader.Close towards the bottom of the
While Loop it still doesn't work [The same error is returned].

I am a bit lost know, if anyone has any ideas on how to get this to work it
would be greatly appreciated if you could respond to this query as I am left
with the option of opening every file seperately through different variables
if this doesn't work; and with over 700 files to be opened I am not liking
that option.

Yours sincerely,

William Foster
Click to expand...
Click to expand...
 
William, happy to help and happier you found the problem. :) Debugging
something like this might feel like shooting in the dark :) I was mainly
trying to address your concern that the object isn't clearing. But I'm glad
that the error message was more relevant to the problem than just the object
not clearing.
Thanks,

--
Mohamad Elarabi
Lead Developer. MCTS, MCPD.


William Foster said:
Mohamad,

Thanks for your assistance, on the good side your recommendation has
certainly improved my coding. On the bad side it did not resolve my error;
on further investigation [painful investigation] I found that I had misplaced
a vbCr within a seperate process which was coming into causing the error.

Thanks for your help!

William Foster

Mohamad Elarabi said:
You are currently dimming a single streamreader, not initializing it, and
then initializing it over and over in your loop.

There might be a better way of doing this and it actually confirms that the
object is destroyed. That is by using the "Using" clause. The "Using" clause
makes sure the object is completely destroyed outside the Using range.

Example:

While . . .
'Insert code to populate sFilePath
Using Import_File_Reader as New System.IO.StreamReader(sFilePath)
... Extract data from file. etc
'No need to destroy the file reader it is automatically destroyed by
the engine.
End Using
End While

Let me know if that helps. Good luck.

--
Mohamad Elarabi
Lead Developer. MCTS, MCPD.


William Foster said:
Good evening all,

I am trying to write a process that uses a while loop to cycle multiple
files from an array throught the StreamReader Process.

The whole thing works using:

Dim Import_File_Reader As System.IO.StreamReader

While ...
Import_File_Reader = New StreamReader(Import_File_and_Path)
.... Extract all the data I want then start again ....
End While

However, when I get to the second run through it always return an error
saying that there was an illegal character included in the
Import_File_and_Path variable; on checking there are no illegal characters.
All I can think is that without closing off the Import_File_Reader variable
before running through the While loop for a second time it will not work,
however, when I add in Import_File_Reader.Close towards the bottom of the
While Loop it still doesn't work [The same error is returned].

I am a bit lost know, if anyone has any ideas on how to get this to work it
would be greatly appreciated if you could respond to this query as I am left
with the option of opening every file seperately through different variables
if this doesn't work; and with over 700 files to be opened I am not liking
that option.

Yours sincerely,

William Foster
Click to expand...
Click to expand...
Click to expand...
 
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