What is the difference between rb and r b modes in file objects

Question

I am using pickle module in Python and trying different file IO modes     works on windows    rb  with open pickle f   rb   as fhand          obj   pickle load fhand     works on linux    r  with open pickle f   r   as fhand          obj   pickle load fhand     works on both  r b  with open pickle f   r b   as fhand          obj   pickle load fhand    I never read about  r b  mode anywhere  but found mentioning about it in the documentation   I am getting EOFError on Linux if I use  rb  mode and on Windows if  r  is used  I just gave  r b  mode a shot and it s working on both   What s  r b  mode  What s the difference between  rb  and  r b   Why does it work when the others don t

User · Accepted Answer

r  is used for reading  and writing mode  b is for binary  r b mode is open the binary file in read or write mode  You can read more here

User · Answer

r opens for reading  whereas r  opens for reading and writing  The b is for binary  This is spelled out in the documentation   The most commonly-used values of mode are  r  for reading   w  for writing  truncating the file if it already exists   and  a  for appending  which on some Unix systems means that all writes append to the end of the file regardless of the current seek position   If mode is omitted  it defaults to  r   The default is to use text mode  which may convert   n  characters to a platform-specific representation on writing and back on reading  Thus  when opening a binary file  you should append  b  to the mode value to open the file in binary mode  which will improve portability   Appending  b  is useful even on systems that don   t treat binary and text files differently  where it serves as documentation   See below for more possible values of mode  Modes  r     w   and  a   open the file for updating  note that  w   truncates the file   Append  b  to the mode to open the file in binary mode  on systems that differentiate between binary and text files  on systems that don   t have this distinction  adding the  b  has no effect

User · Answer

My understanding is that adding r  opens for both read and write  just like w   though as pointed out in the comment  will truncate the file   The b just opens it in binary mode  which is supposed to be less aware of things like line separators  at least in C

User · Answer

On Windows   b  appended to the mode opens the file in binary mode  so   there are also modes like  rb    wb   and  r b   Python on Windows   makes a distinction between text and binary files  the end-of-line   characters in text files are automatically altered slightly when data   is read or written  This behind-the-scenes modification to file data   is fine for ASCII text files  but it   ll corrupt binary data like that   in JPEG or EXE files  Be very careful to use binary mode when reading   and writing such files  On Unix  it doesn   t hurt to append a  b  to   the mode  so you can use it platform-independently for all binary   files     Source  Reading and Writing Files

[python] What is the difference between rb and r+b modes in file objects

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