I have the following code:
from sys import argv
script, filename = argv
txt = open(filename)
print "Here's your file %r:" % filename
print txt.read()
print "Type the filename again:"
file_again = raw_input("> ")
txt_again = open(file_again)
print txt_again.read()
And in one of the exercises in my book it says "Have your script also do a close() on the txt and txt_again variables. It’s important to close files when you are done with them.
How can I close the variables?
txt.close() will close the file parser. However I would suggest the use of with instead:
with open(filename) as txt:
print "Here's your file %r:" % filename
print txt.read()
print "Type the filename again:"
file_again = raw_input("> ")
with open(file_again) as txt_again
print txt_again.read()
This ensures that the file parser is closed correctly and also make for cleaner more pythonic code.
Do txt.close() and txt_again.close() after their respective print statements.
EDIT: As others have already pointed out, using the with statement is a much better option.
Your book text is being unclear and imprecise. What they want you to do is call the file.close() method on the file objects:
print txt.read()
txt.close()
and
print txt_again.read()
txt_again.close()
A better idea would be to use the with statement to have Python close files for you automatically; file objects are context managers:
with open(filename) as txt:
print "Here's your file %r:" % filename
print txt.read()
print "Type the filename again:"
file_again = raw_input("> ")
with open(file_again) as txt_again:
print txt_again.read()
The with statement tells the file object that a block begins (entering the context), and when the indented section ends the statement informs the file object the block has completed (exiting the context). A file object automatically closes itself at that point.
Use txt.close().
It's also worth noting that you are not closing a varibale, but rather a handle on the file.
txt.close();txt_again.close(). Btw you're not closing variables. You're closing the file objects.withcan be used to alleviate manually management. e.g see docs.python.org/3/reference/… , stackoverflow.com/questions/4042995/…with, which will handle the closing for you even in case of exception.