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Writting text to file c#.it's being used by another process

I am creating a text file and after that I am trying to write some text in that file.but when writing text,it's generating exception that process cannot access file because it's being used by another process. Kindly someone help :( Thanks in advance.
Here is my code
dt_Loc = loc1_ctab.GetEmpLocInfo(Session["empcd"].ToString());
string str = DateTime.Now.ToString("dd-mmm-yyyy");
str = dt_Loc.Rows[0]["loc1_abrv"].ToString() + "-" + str;
string path = FilesPath.Path_SaveFile + str + ".txt";
if (!File.Exists(path))
{
File.Create(path);
TextWriter tw = new StreamWriter(path);
tw.WriteLine(txt_comments.Text);
tw.Close();
}

Remove the File.Create since it opens a FileStream for the file.This results in the file being open and hence you get the exception that the file is being used by another process.
if (!File.Exists(path))
{
using(StreamWriter sw = new StreamWriter(path))
{
sw.WriteLine(txt_comments.Text);
}
}

Your code giving such error because, the method Create Creates or overwrites a file in the specified path. which will return A FileStream that provides read/write access to the file specified in path. So at the time of executing the writemethod, the file is being used by the returned FS. you can use this in the following way:
using (FileStream fs = File.Create(path))
{
Byte[] info = new UTF8Encoding(true).GetBytes(txt_comments.Text);
// Add some information to the file.
fs.Write(info, 0, info.Length);
}
You can Make it simple by using File.WriteAllText which will Creates a new file, write the contents to the file, and then closes the file. If the target file already exists, it is overwritten.
string path =FilesPath.Path_SaveFile + str + ".txt";;
if (!File.Exists(path))
{
File.WriteAllText(path, txt_comments.Text);
}

Working with .tmp file for writing data

I'm wondering if there is a best practice when it comes to working with .tmp file for writing data. I like to make an .tmp that will be use in the filestream and then when I close the writer, I like to rename the file. Is there a way to rename file extension?
FileStream stream2 = new FileStream(fileName, FileMode.Create, FileAccess.ReadWrite);
StreamWriter streamWriter2 = new StreamWriter(stream2);
streamWriter2.WriteLine(textToAdd);
streamWriter2.Close();
string changed = Path.ChangeExtension(fileName, .txt);
File.Move(path, changed);

Here's how I would do this:
// Build a FileInfo object for your temp destination, this gives us
// access to a handful of useful file manipulation methods
var yourFile = new FileInfo(#"C:\temp\testfile.tmp");
// open a StreamWriter to write text to the file
using (StreamWriter sw = yourFile.CreateText())
{
// Write your text
sw.WriteLine("Test");
// There's no need to call Close() when you're using usings
}
// "Rename" the file -- this is the fastest way in C#
yourFile.MoveTo(#"C:\temp\testfile.txt");

You can use Path.GetFilenameWithoutExtension to remove the extension and then just add the one you want.

Create and write file txt

How can I create and then modify writing on this file?
string fileName = #"C:\...\MioFile.txt";
In main:
File.CreateText(fileName);
Then when I would edit the file by adding text.
StreamWriter writer = new StreamWriter(fileName);
sw.WriteLine("Hello"+variable);
sw.Close();
But the file is empty and I cannot write anything.
I would like create a file.txt and I would like for this file to always add new information every time I call it in writing mode. A kind of "log file".

Use File.AppendAllText instead of StreamWriter. Its simple:
File.AppendAllText(filename, "Hello"+variable);

You have sw.WriteLine, But your streamwriter is called "writer". That might be the problem.

I like to use the "using" statements:
//full path
var fileName = #"C:\Users\...\Desktop\newFile2.txt";
//Get the stream in FileMode.Append (will create or open)
using (var fileStream = new FileStream(fileName,FileMode.Append))
{
//pass the fileStream into the writer.
using (var writer = new StreamWriter(fileStream))
{
writer.WriteLine("{0} => file appended", DateTime.Now);
}//dispose writer
}//dispose fileStream

"File in use" error when writing to text file

I'm getting the error The process cannot access the file 'C:\Users\Ryan\Desktop\New folder\POSData.txt' because it is being used by another process. when I try to create a file and then write to it. What process is using the file?? I checked for a file.close to call after I create the file, but it doesn't exist. How do I get past this? Thanks!
Heres my code:
MessageBox.Show("Please select a folder to save your database to.");
this.folderBrowserDialog1.RootFolder = System.Environment.SpecialFolder.Desktop;
DialogResult result = this.folderBrowserDialog1.ShowDialog();
if (result == DialogResult.OK)
{
databasePath = folderBrowserDialog1.SelectedPath;
if (!File.Exists(databasePath + "\\POSData.txt"))
{
File.Create(databasePath + "\\POSData.txt");
}
using (StreamWriter w = new StreamWriter(databasePath + "\\POSData.txt", false))
{
w.WriteLine(stockCount);
}
}
Edit: Only happens when creating the file. If it already exists, no error occurs.

Actually, don't even bother using File.Create. The reason you're getting that error is because File.Create is opening up a stream on that text file.
string filePath = "databasePath + "\\POSData.txt"";
using (StreamWriter sw = new StreamWriter(filePath, true))
{
//write to the file
}

You are keeping the file open when you call File.Create (i.e. you never close the file).
StreamWriter will create the file for you if it doesn't exist, so I wouldn't bother checking yourself. You could just remove the code that checks whether it exists and creates it if it doesn't.
if (result == DialogResult.OK)
{
databasePath = folderBrowserDialog1.SelectedPath;
using (StreamWriter w = new StreamWriter(databasePath + "\\POSData.txt", false))
{
w.WriteLine(stockCount);
}
}
Note that if the file doesn't exist, the second bool parameter in the StreamWriter constructor is ignored.

File.Create also opens the file for reading/writing. As such, you're leaving an open FileStream when you File.Create.
Assuming that overwriting is OK, then you probably want to do something like this:
using (var fs = File.Create(databasePath + "\\POSData.txt"))
using (StreamWriter w = new StreamWriter(fs))
{
w.WriteLine(stockCount);
}
given that File.Create:
Creates or overwrites a file in the specified path.

The File.Create returns a FileStream object that might need to be closed.
The FileStream object created by this method has a default FileShare
value of None; no other process or code can access the created file
until the original file handle is closed.
using (FileStream fs = File.Create(databasePath + "\\POSData.txt"))
{
fs.Write(uniEncoding.GetBytes(stockCount), 0, uniEncoding.GetByteCount(stockCount));
}

I used this and it worked
`File.AppendAllText(fileName,"");`
This creates a new file, writes nothing to it, then closes it for you.

"The process cannot access the file because it is being used by another process" with Images

I've seen many issues like this that have been solved and the problem was mostly due to streams not being disposed of properly.
My issue is slightly different, here follow a code snippet
foreach (Images item in ListOfImages)
{
newPath = Path.Combine(newPath, item.ImageName + item.ImageExtension);
File.Create(newPath);
File.WriteAllBytes(newPath, item.File);
}
Where Images is a custom struct and item.File is the raw data, byte[].
My issue is that at the line where the WriteAllBytes is called, an exception is thrown. The message reads:
The process cannot access the file because it is being used by another process
Again I have no clue how am I going to somehow close the process.

Since File.Create returns the stream i would dispose it properly:
using(var stream = File.Create(newPath)){}
File.WriteAllBytes(newPath, item.File);
or you can use the stream to write to the file directly:
using (FileStream fs = File.Create(newPath))
{
fs.Write(item.File, 0, item.File.Length);
}
or, probably the easiest, use File.WriteAllBytes alone:
File.WriteAllBytes(newPath, item.File);
Creates a new file, writes the specified byte array to the file, and
then closes the file. If the target file already exists, it is
overwritten.

You state that your problem has nothing to do with disposing streams but check this MSDN article:
http://msdn.microsoft.com/en-us/library/d62kzs03.aspx
What does File.Create return? A FileStream!!!!
And, at the end of the day, why are you using File.Create if File.WriteAllBytes creates a file if this doesn't exist? ;)
Creates a new file, writes the specified byte array to the file, and
then closes the file. If the target file already exists, it is
overwritten.
Check it on MSDN too: http://msdn.microsoft.com/en-us/library/system.io.file.writeallbytes.aspx

using (FileStream fs =
new FileStream(filePath,
FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
Your log may be write locked, so try with FileShare.ReadWrite.

The create method opens the file for writing and returns a FileStream object for you to work with. Just because you are not referencing it does not mean it does not need to be returned.
foreach (Images item in ListOfImages)
{
newPath = Path.Combine(newPath, item.ImageName + item.ImageExtension);
FileStream f = File.Create(newPath);
f.Write(item.File, 0, item.File.Length);
}

The File.WriteAllBytes creates the file if necessary. You can juts use:
foreach (Images item in ListOfImages)
{
newPath = Path.Combine(newPath, item.ImageName + item.ImageExtension);
File.WriteAllBytes(newPath, item.File);
}
And are you combine path correctly?

This is the most specific way to accomplish what you are trying to do:
foreach (Images item in ListOfImages)
{
using (System.IO.FileStream output = new System.IO.FileStream(Path.Combine(newPath, item.ImageName + item.ImageExtension),
System.IO.FileMode.Create, System.IO.FileAccess.Write))
{
output.Write(item.File, 0, item.File.Length);
output.Flush();
output.Close();
}
}
You also need to fix your logic for creating the path, which I have done in my example above. You were concatenating the newPath over and over again.

Force the garbage collector to clean.
GC.Collect();