[Tutor] file opened by open() are closed automaticaly
ben+python at benfinney.id.au
Sat Jan 14 06:04:21 EST 2017
ZEMMOURA Khalil Zakaria <zemmoura.khalil at gmail.com> writes:
> The file opened using open() is closed automaticaly after iterationg
> over it in the python shell
You can interrogate a file to ask whether it is closed; the ‘closed’
attribute will be True when the file is closed.
> testfile = open('test.txt')
> for line in testfile:
What happens if you insert this line before the ‘print’ statement::
for line in testfile:
assert (not testfile.closed), "file was closed unexpectedly!"
If what you say is true, that ‘assert’ statement will raise an exception
with that custom message.
> the first time the code runs well and gives me the expected result.
> the secod time that i run the loop, nothing is printed on the screen.
If you try to read from a file that is already closed, an error occurs::
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: I/O operation on closed file.
But you're not getting that error. So, some other reason explains the
lack of output.
\ “… whoever claims any right that he is unwilling to accord to |
`\ his fellow-men is dishonest and infamous.” —Robert G. |
_o__) Ingersoll, _The Liberty of Man, Woman and Child_, 1877 |
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