Writing to a new file if it doesn t exist and appending to a file if it does

Question

I have a program which writes a user s highscore to a text file  The file is named by the user when they choose a playername    If the file with that specific username already exists  then the program should append to the file  so that you can see more than one highscore   And if a file with that username doesn t exist  for example  if the user is new   it should create a new file and write to it   Here s the relevant  so far not working  code   try       with open player    player is the varible storing the username input         with open player   a   as highscore              highscore write  Username    player   except IOError      with open player     txt    w   as highscore          highscore write  Username    player    The above code creates a new file if it doesn t exist  and writes to it  If it exists  nothing has been appended when I check the file  and I get no errors

User · Accepted Answer

It s not clear to me exactly where the high-score that you re interested in is stored  but the code below should be what you need to check if the file exists and append to it if desired  I prefer this method to the  try except    import os player    bob   filename   player   txt   if os path exists filename       append write    a    append if already exists else      append write    w    make a new file if not  highscore   open filename append write  highscore write  Username      player     n   highscore close

User · Answer

Notice that if the file s parent folder doesn t exist you ll get the same error   IOError   Errno 2  No such file or directory   Below is another solution which handles this case       I used sys stdout and print instead of f write just to show another use case   Make sure the file s folder exist - Create folder if doesn t exist folder path    path to   folder name     if not os path exists folder path        os makedirs folder path   print to log file folder path   quot Some File quot    quot Some Content quot    Where the internal print to log file just take care of the file level    If you re not familiar with sys stdout - just ignore it below  just a use case example  def print to log file folder path  file name  content to write        1  Save a reference to the original standard output            original stdout   sys stdout              2  Choose the mode     write append mode    a   Append mode     file path   folder path   file name     if  if not os path exists file path            write append mode    w    Write mode            3  Perform action on file     with open file path  write append mode  as f          sys stdout   f    Change the standard output to the file we created          print file path  content to write          sys stdout   original stdout    Reset the standard output to its original value   Consider the following states   w   -- gt  Write to existing file  w   -- gt  Write to file  Create it if doesn t exist  a   -- gt  Append to file  a   -- gt  Append to file  Create it if doesn t exist  In your case I would use a different approach and just use  a  and  a

User · Answer

Have you tried mode  a     with open filename   a    as f      f write        Note however that f tell   will return 0 in Python 2 x  See https   bugs python org issue22651 for details

User · Answer

Just open it in  a  mode      a  nbsp  Open for writing  The file is created if it does not exist  The stream is positioned at the end of the file    with open filename   a   as f      f write        To see whether you re writing to a new file  check the stream position  If it s zero  either the file was empty or it is a new file   with open  somefile txt    a   as f      if f tell      0          print  a new file or the file was empty           f write  The header n       else          print  file existed  appending       f write  Some data n     If you re still using Python 2  to work around the bug  either add f seek 0  os SEEK END  right after open or use io open instead

User · Answer

Using the pathlib module  python s object-oriented filesystem paths  Just for kicks  this is perhaps the latest pythonic version of the solution  from pathlib import Path   path   Path f  player  txt   path touch      default exists ok True with path open  a   as highscore     highscore write f Username  player

[python] Writing to a new file if it doesn't exist, and appending to a file if it does

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