GNU Info

(python2.1-tut.info)Reading and Writing Files

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Enter node , (file) or (file)node

Reading and Writing Files
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`open()'  returns a file object , and is most commonly used with two
arguments: `open(FILENAME, MODE)'.

     >>> f=open('/tmp/workfile', 'w')
     >>> print f
     <open file '/tmp/workfile', mode 'w' at 80a0960>

The first argument is a string containing the filename.  The second
argument is another string containing a few characters describing the
way in which the file will be used.  MODE can be `'r'' when the file
will only be read, `'w'' for only writing (an existing file with the
same name will be erased), and `'a'' opens the file for appending; any
data written to the file is automatically added to the end.  `'r+''
opens the file for both reading and writing.  The MODE argument is
optional; `'r'' will be assumed if it's omitted.

On Windows and the Macintosh, `'b'' appended to the mode opens the file
in binary mode, so there are also modes like `'rb'', `'wb'', and
`'r+b''.  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 JPEGs or `.EXE' files.  Be very
careful to use binary mode when reading and writing such files.  (Note
that the precise semantics of text mode on the Macintosh depends on the
underlying C library being used.)

Methods of File Objects

pickle Module