I am trying to write a log file, but it constantly says "File being used by another process". Here's my code:
//_logFile = "system.log"
if(!File.Exists(Path.Combine("logs", _logFile)))
{
File.Create(Path.Combine("logs", _logFile)).Close();
sw = File.AppendText(Path.Combine("logs", _logFile));
}
else
{
sw = File.AppendText(Path.Combine("logs", _logFile));
}
When I run it, it points to the File.Create(Path.Combine("logs", _logFile)).Close() line and gives me the error.
Edit:
I changed if(!File.Exists(_logFile)) to if(!File.Exists(Path.Combine("logs", _logFile))) but I still get the same error.
Assuming you don't need access to this stream outside the context of this method, I'd refactor your code to this:
var filePath = Path.Combine("logs", _logFile);
using (var sw = File.AppendText(filePath))
{
//Do whatever writing to stream I want.
sw.WriteLine(DateTime.Now.ToString() + ": test log entry");
}
This way, no matter what happens inside the using block, you know the file will be closed so you can use it again later.
Note that File.AppendText will create the file if it doesn't already exist, so File.Create is not needed.
Related
I'm trying to detect if a file exists at runtime, if not, create it. However I'm getting this error when I try to write to it:
The process cannot access the file 'myfile.ext' because it is being used by another process.
string filePath = string.Format(#"{0}\M{1}.dat", ConfigurationManager.AppSettings["DirectoryPath"], costCentre);
if (!File.Exists(filePath))
{
File.Create(filePath);
}
using (StreamWriter sw = File.AppendText(filePath))
{
//write my text
}
Any ideas on how to fix it?
File.Create(FilePath).Close();
File.WriteAllText(FileText);
I want to update this answer to say that this is not really the most efficient way to write all text. You should only use this code if you need something quick and dirty.
I was a young programmer when I answered this question, and back then I thought I was some kind of genius for coming up with this answer.
The File.Create method creates the file and opens a FileStream on the file. So your file is already open. You don't really need the file.Create method at all:
string filePath = #"c:\somefilename.txt";
using (StreamWriter sw = new StreamWriter(filePath, true))
{
//write to the file
}
The boolean in the StreamWriter constructor will cause the contents to be appended if the file exists.
When creating a text file you can use the following code:
System.IO.File.WriteAllText("c:\test.txt", "all of your content here");
Using the code from your comment. The file(stream) you created must be closed. File.Create return the filestream to the just created file.:
string filePath = "filepath here";
if (!System.IO.File.Exists(filePath))
{
System.IO.FileStream f = System.IO.File.Create(filePath);
f.Close();
}
using (System.IO.StreamWriter sw = System.IO.File.AppendText(filePath))
{
//write my text
}
FileStream fs= File.Create(ConfigurationManager.AppSettings["file"]);
fs.Close();
File.Create returns a FileStream. You need to close that when you have written to the file:
using (FileStream fs = File.Create(path, 1024))
{
Byte[] info = new UTF8Encoding(true).GetBytes("This is some text in the file.");
// Add some information to the file.
fs.Write(info, 0, info.Length);
}
You can use using for automatically closing the file.
I updated your question with the code snippet. After proper indenting, it is immediately clear what the problem is: you use File.Create() but don't close the FileStream that it returns.
Doing it that way is unnecessary, StreamWriter already allows appending to an existing file and creating a new file if it doesn't yet exist. Like this:
string filePath = string.Format(#"{0}\M{1}.dat", ConfigurationManager.AppSettings["DirectoryPath"], costCentre);
using (StreamWriter sw = new StreamWriter(filePath, true)) {
//write my text
}
Which uses this StreamWriter constructor.
I know this is an old question, but I just want to throw this out there that you can still use File.Create("filename")", just add .Dispose() to it.
File.Create("filename").Dispose();
This way it creates and closes the file for the next process to use it.
This question has already been answered, but here is a real world solution that
checks if the directory exists and adds a number to the end if the text file
exists. I use this for creating daily log files on a Windows service I wrote. I
hope this helps someone.
// How to create a log file with a sortable date and add numbering to it if it already exists.
public void CreateLogFile()
{
// filePath usually comes from the App.config file. I've written the value explicitly here for demo purposes.
var filePath = "C:\\Logs";
// Append a backslash if one is not present at the end of the file path.
if (!filePath.EndsWith("\\"))
{
filePath += "\\";
}
// Create the path if it doesn't exist.
if (!Directory.Exists(filePath))
{
Directory.CreateDirectory(filePath);
}
// Create the file name with a calendar sortable date on the end.
var now = DateTime.Now;
filePath += string.Format("Daily Log [{0}-{1}-{2}].txt", now.Year, now.Month, now.Day);
// Check if the file that is about to be created already exists. If so, append a number to the end.
if (File.Exists(filePath))
{
var counter = 1;
filePath = filePath.Replace(".txt", " (" + counter + ").txt");
while (File.Exists(filePath))
{
filePath = filePath.Replace("(" + counter + ").txt", "(" + (counter + 1) + ").txt");
counter++;
}
}
// Note that after the file is created, the file stream is still open. It needs to be closed
// once it is created if other methods need to access it.
using (var file = File.Create(filePath))
{
file.Close();
}
}
I think I know the reason for this exception. You might be running this code snippet in multiple threads.
you can just use using keyword around File.Create(path) to finalize the process
using(File.Create(path));
Try this: It works in any case, if the file doesn't exists, it will create it and then write to it. And if already exists, no problem it will open and write to it :
using (FileStream fs= new FileStream(#"File.txt",FileMode.Create,FileAccess.ReadWrite))
{
fs.close();
}
using (StreamWriter sw = new StreamWriter(#"File.txt"))
{
sw.WriteLine("bla bla bla");
sw.Close();
}
I am getting this error when i am trying to write to a file in this manner:
try
{
if (!File.Exists(path))
File.CreateText(file.ToString());
sw = flag == 1 ? File.CreateText(file.ToString()) : File.AppendText(file.ToString()); //Exception here
sw.WriteLine(textToWrite);
status = true;
}
But before to this file i made a delete attempt to it also in another function in this way:
try
{
File.Delete(path);
status = true;
}
Exception:
{"The process cannot access the file ... because it is being used by another process."}
Now as it seems file is still either taken by delete process of by the File.CreateText function, how can i make them release the file so i can start writing to it?
File.CreateText will return a streamwriter which has a file stream still opened. You should be using that. That is the reason why you get exception in successive calls to open the file.
Try this.
using(var sw = File.CreateText(...))
{
//Do whatever
}
If you want to delete the file before writing a new file, try this:
File.WriteAllText(path, textToWrite);
If you want to append to a file (or create), try this:
File.AppendAllText(path, textToWrite);
Both of these methods close the file after writing.
CreateText returns StremWriter which you miss it. That's why it remains opened. You can easily close it:
StreamReader sr = File.OpenText(path);
sr.WriteLine(textToWrite);
sr.Close();
I've been trying to come up with a way for my code to open a file or create one (if my given file name is non-existent). Afterwards, it will run a program that will end up creating an array and I want the contents of that array to be converted into string and appended into the file that I am creating and opening. I've got everything right except for the 'Append' part. It say in the end that the "Object reference not set to an instance of an object." Can you please enlighten me on this one? Help will be much appreciated.
try
{
FileStream fs = new FileStream("inventory.ini", FileMode.OpenOrCreate, FileAccess.Read);
StreamReader reader = new StreamReader(fs);
while (!reader.EndOfStream)
{
string line = reader.ReadLine();
string[] data = line.Split('|');
int code = int.Parse(data[0]);
string name = data[1];
double price = double.Parse(data[2]);
Item item = new Item(code, name, price);
app.array[inventoryCount++] = item;
}
reader.Close();
fs.Close();
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
app.Run();
try
{
FileStream fs = new FileStream("inventory.ini", FileMode.Append, FileAccess.Write);
StreamWriter writer = new StreamWriter(fs);
foreach (Item item in app.array)
{
writer.WriteLine(item.Code + "|" + item.Name + "|" + item.Price);
}
writer.Close();
fs.Close();
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
Console.ReadLine();
}
You can use another constructor of StreamWriter, that allows appending, and then write like this:
StreamWriter writer = new StreamWriter("inventory.ini", true);
I never used FileStream in my apps, but StreamWriter has been quite reliable. You can also switch to Using statement, then you don't need to Close().
Also I suggest switching to lists, then you will always have the exact amount of items you need inside app.array (which btw needs a better name). So this:
app.array[inventoryCount++] = item;
will change to something like this:
app.list.Add(item);
Aside from memory management headache relief, you no longer need inventoryCount variable, since you can get this value from list.Count;
The general approach here is to minimize amount of code you need to write, for the same amount of functionality. Then you have no place for the error to lurk.
catch (Exception e)
{
Console.WriteLine(e.Message);
}
You are digging yourself a pretty deep hole with exception handling like this. A hard rule in catching an exception is that you restore the state of your program when you handle it. You don't. In particular, you are forgetting to close the file. This then goes wrong, later, when you try to open the file again to write. The exception message is misleading, unfortunately, talking about another process having the file already opened. Not the case, it is your process that still has the file opened.
There are plenty of countermeasures against this failure. You should be using the using statement to ensure the file is closed even if there's an exception. And you'll need to fix your EndOfStream test, it isn't accurate on text files, use a while(true) loop and break when ReadLine() returns null. Which solves the original problem.
But the real fix is to not hide an inconvenient truth. Allowing your program to continue running when a config file is broken just begets more trouble when it doesn't do what you hope it does. And you can't tell because the message you write to the console was scrolled off the screen. Very hard to diagnose.
Remove the try/catch from this code. Now you get to address the real problem.
Note that you can also just use File.AppendText() to open a StreamWriter in append mode.
You should also use using instead of .Close() to close the stream - then it will work even if an exception occurs.
So your code would look more like this:
try
{
using (var writer = File.AppendText("inventory.ini"))
{
foreach (Item item in app.array)
{
if (item != null)
writer.WriteLine(item.Code + "|" + item.Name + "|" + item.Price);
}
}
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
Why don't you use using statement
using (FileStream fs = new FileStream("inventory.ini", FileMode.OpenOrCreate, FileAccess.Read))
using (StreamReader reader = new StreamReader(fs))
{
// do stuff
}
I'm trying to detect if a file exists at runtime, if not, create it. However I'm getting this error when I try to write to it:
The process cannot access the file 'myfile.ext' because it is being used by another process.
string filePath = string.Format(#"{0}\M{1}.dat", ConfigurationManager.AppSettings["DirectoryPath"], costCentre);
if (!File.Exists(filePath))
{
File.Create(filePath);
}
using (StreamWriter sw = File.AppendText(filePath))
{
//write my text
}
Any ideas on how to fix it?
File.Create(FilePath).Close();
File.WriteAllText(FileText);
I want to update this answer to say that this is not really the most efficient way to write all text. You should only use this code if you need something quick and dirty.
I was a young programmer when I answered this question, and back then I thought I was some kind of genius for coming up with this answer.
The File.Create method creates the file and opens a FileStream on the file. So your file is already open. You don't really need the file.Create method at all:
string filePath = #"c:\somefilename.txt";
using (StreamWriter sw = new StreamWriter(filePath, true))
{
//write to the file
}
The boolean in the StreamWriter constructor will cause the contents to be appended if the file exists.
When creating a text file you can use the following code:
System.IO.File.WriteAllText("c:\test.txt", "all of your content here");
Using the code from your comment. The file(stream) you created must be closed. File.Create return the filestream to the just created file.:
string filePath = "filepath here";
if (!System.IO.File.Exists(filePath))
{
System.IO.FileStream f = System.IO.File.Create(filePath);
f.Close();
}
using (System.IO.StreamWriter sw = System.IO.File.AppendText(filePath))
{
//write my text
}
FileStream fs= File.Create(ConfigurationManager.AppSettings["file"]);
fs.Close();
File.Create returns a FileStream. You need to close that when you have written to the file:
using (FileStream fs = File.Create(path, 1024))
{
Byte[] info = new UTF8Encoding(true).GetBytes("This is some text in the file.");
// Add some information to the file.
fs.Write(info, 0, info.Length);
}
You can use using for automatically closing the file.
I updated your question with the code snippet. After proper indenting, it is immediately clear what the problem is: you use File.Create() but don't close the FileStream that it returns.
Doing it that way is unnecessary, StreamWriter already allows appending to an existing file and creating a new file if it doesn't yet exist. Like this:
string filePath = string.Format(#"{0}\M{1}.dat", ConfigurationManager.AppSettings["DirectoryPath"], costCentre);
using (StreamWriter sw = new StreamWriter(filePath, true)) {
//write my text
}
Which uses this StreamWriter constructor.
I know this is an old question, but I just want to throw this out there that you can still use File.Create("filename")", just add .Dispose() to it.
File.Create("filename").Dispose();
This way it creates and closes the file for the next process to use it.
This question has already been answered, but here is a real world solution that
checks if the directory exists and adds a number to the end if the text file
exists. I use this for creating daily log files on a Windows service I wrote. I
hope this helps someone.
// How to create a log file with a sortable date and add numbering to it if it already exists.
public void CreateLogFile()
{
// filePath usually comes from the App.config file. I've written the value explicitly here for demo purposes.
var filePath = "C:\\Logs";
// Append a backslash if one is not present at the end of the file path.
if (!filePath.EndsWith("\\"))
{
filePath += "\\";
}
// Create the path if it doesn't exist.
if (!Directory.Exists(filePath))
{
Directory.CreateDirectory(filePath);
}
// Create the file name with a calendar sortable date on the end.
var now = DateTime.Now;
filePath += string.Format("Daily Log [{0}-{1}-{2}].txt", now.Year, now.Month, now.Day);
// Check if the file that is about to be created already exists. If so, append a number to the end.
if (File.Exists(filePath))
{
var counter = 1;
filePath = filePath.Replace(".txt", " (" + counter + ").txt");
while (File.Exists(filePath))
{
filePath = filePath.Replace("(" + counter + ").txt", "(" + (counter + 1) + ").txt");
counter++;
}
}
// Note that after the file is created, the file stream is still open. It needs to be closed
// once it is created if other methods need to access it.
using (var file = File.Create(filePath))
{
file.Close();
}
}
I think I know the reason for this exception. You might be running this code snippet in multiple threads.
you can just use using keyword around File.Create(path) to finalize the process
using(File.Create(path));
Try this: It works in any case, if the file doesn't exists, it will create it and then write to it. And if already exists, no problem it will open and write to it :
using (FileStream fs= new FileStream(#"File.txt",FileMode.Create,FileAccess.ReadWrite))
{
fs.close();
}
using (StreamWriter sw = new StreamWriter(#"File.txt"))
{
sw.WriteLine("bla bla bla");
sw.Close();
}
I am trying to write some text to the file using StreamWriter and getting the
path for the file from FolderDialog selected folder. My code works fine if the
file does not already exist. but if the file already exist it throws the Exception
that the file is in used by other process.
using(StreamWriter sw = new StreamWriter(FolderDialog.SelectedPath + #"\my_file.txt")
{
sw.writeLine("blablabla");
}
Now if I write like this:
using(StreamWriter sw = new StreamWriter(#"C:\some_folder\my_file.txt")
it works fine with an existing file.
It may have to do with the way you are combining your path and filename. Give this a try:
using(StreamWriter sw = new StreamWriter(
Path.Combine(FolderDialog.SelectedPath, "my_file.txt"))
{
sw.writeLine("blablabla");
}
Also, check to make sure the FolderDialog.SelectedPath value isn't blank. :)
The file is already in use, so it cannot be overwritten. However, note that this message isn't always entirely accurate - the file may in fact be in use by your own process. Check your usage patterns.
This is a cheap answer, but have you tried this workaround?
string sFileName= FolderDialog.SelectedPath + #"\my_file.txt";
using(StreamWriter sw = new StreamWriter(sFileName))
{
sw.writeLine("blablabla");
}
The other thing I would suggest is verifying that FolderDialog.SelectedPath + "\my_file.txt" is equal to the hard coded path of "C:\some_folder\my_file.txt".
Check whether the file is in fact in use by some other process.
To do that, run Process Explorer, press Ctrl+F, type the filename, and click Find.
As an aside, the best way to accomplish this task is like this:
using(StreamWriter sw = File.AppendText(Path.Combine(FolderDialog.SelectedPath, #"my_file.txt")))
EDIT: Do NOT put a slash in the second argument to Path.Combine.
Try this
using (StreamWriter sw = File.AppendText(#"C:\some_folder\my_file.txt"))
{
sw.writeLine("blablabla");
}
it will only work in existing file, so to validate if the file is new or already exists, do something like
string path = #"C:\some_folder\my_file.txt";
if (!File.Exists(path))
{
// Create a file to write to.
using (StreamWriter sw = File.CreateText(path))
{
//once file was created insert the text or the columns
sw.WriteLine("blbalbala");
}
}
// if already exists just write
using (StreamWriter sw = File.AppendText(#"C:\some_folder\my_file.txt"))
{
sw.writeLine("blablabla");
}