File being used by another process after using File Create

Question

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

User · Accepted 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

User · Answer

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

User · Answer

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

User · Answer

FileStream fs  File Create ConfigurationManager AppSettings  file     fs Close

User · Answer

I think I know the reason for this exception  You might be running this code snippet in multiple threads

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

[c#] File being used by another process after using File.Create()

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