I/O operations.

Posted on 2003-03-24
Medium Priority
Last Modified: 2010-04-15

Hi group, I want to write to a file when an exception ocurs,
I use the FilseStream and StreamWrite classes.

This is the code:
//Creates the FileStream and StreamWrite object
if (File.Exists(fileName))


fs = new FileStream(fileName,FileMode.Open,FileAccess.Write);

sw = new StreamWriter(fs);




fs = new FileStream(fileName,FileMode.Create);

sw = new StreamWriter(fs);


//The code that writes into a file


//buffer the string that I want to write



catch(Exception e)




It's seems to work but doesn't write anything in the file.
Question by:alarcia
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Accepted Solution

Nebulus_ earned 80 total points
ID: 8193638
I think that you must flush the StreamWriter. This can be done automatically after you create the sw object:

sw.AutoFlush = true;

or manually:


after each write op.

Expert Comment

ID: 8196996
One additional point;

your first if-statement to create a new FileStream is not actually necessary, since the FileMode 'Create' will create a new file if is does not exists, or open the file if it does exist.

You are also not specifiying a FileAccess parameter for your second FileStream, so be sure to check what the Default Access is, since it may be 'Read', and you want to 'Write'.

Good luck.
LVL 14

Assisted Solution

AvonWyss earned 80 total points
ID: 8202421
Try it like this:

               using (StreamWriter sw=new StreamWriter(new FileStream(fileName, FileMode.OpenOrCreate, FileAccess.Write), true)) {

- the "using" clause will have the compiler close and dispose the StreamWriter automatically (and therefore also the underlying stream).
- FileMode.Create always deletes an existing file, but OpenOrCreate opens the file if it exists and creates it otherwise.
- The "true" parameter will make sure that data will be appended instead of overwriting existing data in the file.
LVL 14

Expert Comment

ID: 8202428
Even easier...

               using (StreamWriter sw=new StreamWriter(fileName, true)) {

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