traverseda
/
cpython
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Merge: #16273: Fix tutorial discussion of seek/tell (opaque text-mode values).

This commit is contained in:
R David Murray 2013-07-30 15:53:30 -04:00
parent f392c604e7 1c4e443ea2
commit bc47d7bb4f
1 changed files with 9 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
Doc/tutorial/inputoutput.rst
View File

@ -322,9 +322,11 @@ first::
>>> f.write(s)
18
``f.tell()`` returns an integer giving the file object's current position in the
file, measured in bytes from the beginning of the file. To change the file
object's position, use ``f.seek(offset, from_what)``. The position is computed
``f.tell()`` returns an integer giving the file object's current position in the file
represented as number of bytes from the beginning of the file when in `binary mode` and
an opaque number when in `text mode`.
To change the file object's position, use ``f.seek(offset, from_what)``. The position is computed
from adding *offset* to a reference point; the reference point is selected by
the *from_what* argument. A *from_what* value of 0 measures from the beginning
of the file, 1 uses the current file position, and 2 uses the end of the file as
@ -345,7 +347,10 @@ beginning of the file as the reference point. ::
In text files (those opened without a ``b`` in the mode string), only seeks
relative to the beginning of the file are allowed (the exception being seeking
to the very file end with ``seek(0, 2)``).
to the very file end with ``seek(0, 2)``) and the only valid *offset* values are
those returned from the ``f.tell()``, or zero. Any other *offset* value produces
undefined behaviour.
When you're done with a file, call ``f.close()`` to close it and free up any
system resources taken up by the open file. After calling ``f.close()``,