Creating an empty file in C

Question

What s the simplest canonical way to create an empty file in C   NET   The simplest way I could find so far is   System IO File WriteAllLines filename  new string 0

User · Answer

File WriteAllText  path   String Empty     or  File CreateText  path   Close

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Path GetTempFileName   will create a uniquly named empty file and return the path to it   If you want to control the path but get a random file name you can use GetRandomFileName to just return a file name string and use it with Create  For example   string fileName Path GetRandomFileName    File Create  custom  path      fileName

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Using just File Create will leave the file open  which probably isn t what you want   You could use   using  File Create filename       That looks slightly odd  mind you  You could use braces instead   using  File Create filename        Or just call Dispose directly   File Create filename  Dispose      Either way  if you re going to use this in more than one place you should probably consider wrapping it in a helper method  e g   public static void CreateEmptyFile string filename        File Create filename  Dispose        Note that calling Dispose directly instead of using a using statement doesn t really make much difference here as far as I can tell - the only way it could make a difference is if the thread were aborted between the call to File Create and the call to Dispose  If that race condition exists  I suspect it would also exist in the using version  if the thread were aborted at the very end of the File Create method  just before the value was returned

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To avoid accidentally overwriting an existing file use  using  new FileStream filename  FileMode CreateNew          and handle the IOException which will occur if the file already exists  File Create  which is suggested in other answers  will overwrite the contents of the file if it already exists  In simple cases you could mitigate this using File Exists    However something more robust is necessary in scenarios where multiple threads and or processes are attempting to create files in the same folder simultaneously

User · Answer

A somewhat common use case for creating an empty file is to trigger something else happening in a different process in the absence of more sophisticated in process communication  In this case  it can help to have the file creation be atomic from the outside world s point of view  particularly if the thing being triggered is going to delete the file to  consume  the trigger    So it can help to create a junk name  Guid NewGuid ToString    in the same directory as the file you want to create  and then do a File Move from the temporary name to your desired name  Otherwise triggered code which checks for file existence and then deletes the trigger may run into race conditions where the file is deleted before it is fully closed out   Having the temp file in the same directory  and file system  gives you the atomicity you may want  This gives something like   public void CreateEmptyFile string path        string tempFilePath   Path Combine Path GetDirectoryName path           Guid NewGuid ToString         using  File Create tempFilePath          File Move tempFilePath  path

User · Answer

System IO File Create   C  Temp txt      As others have pointed out  you should dispose of this object or wrap it in an empty using statement    using  System IO File Create   C  Temp txt

User · Answer

You can chain methods off the returned object  so you can immediately close the file you just opened in a single statement   File Open  filename   FileMode Create  Close

[c#] Creating an empty file in C#

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