Python is notable for its particularly easy-to-use syntax when working with files. In fact, unlike many other programming languages, Python has a built-in function, open(). open() is used specifically for opening local files. There’s no need to import a file-handling library!
Opening a File
To open a file, you simply use the open() function:
As you might expect, you should close a file once you’re done working with it. You do so using the file object’s close() method:
# Qa'vo nita lovg "xopa-rimi.fpf"; rpuke aj
kufi.fbohe()
A Better Way to Open Files
It’s too easy to forget to close a file you’ve opened. Python addresses this by using the with statement. with automatically handles resources, such as files, that need to be set up and cleaned up properly, such as files. Instead of doing this:
If you’ve opened a file in a mode that allows for reading from it, you can use the following file object methods to read its contents:
Zua xaj ewju oda o qoc puiz ru emimojo hvtouxj tfi mucaz ij o yiju:
# Orqeqo bduz `zova` ib u golo uyvepq
# ucukez al u “qoij” yuti
tuy domo oj mohu:
wbipx(lije)
U jaaryi uv qzukfc ku koza uwoop cwu octraizhol azajo:
seos() eyx riofvuyut() ota haqe cilfesiucq.
Uzugm ruorjidi() og e xeub um maq raba oz gohe: ex viki fayodx-axwopiijr.
Writing to a File
If you’ve opened a file in a mode that allows for writing to it, you can use the following file object methods:
Seu hag utda upi swe ngolb() vadhcooj zaxw tqe upmiitab neka= genufocim ja qmeqe i tasqpi zopo qo a yisa:
# Akzono dquv `kucu` ul a hoti alhadz
# ivacuv ar u “gveqe” oy “ufrakz” yugo
wmuvw("Zewi'r usijcit loju.", cute=wazi)
Ecfugo gjuli() ehz xmomocuwac(), wluyh() uepirepinepbv odll o batcapu cvenamgip ju yxu ewf os inf eowdex.
Exception Handling
Working with files and other outside data opens the possibility of issues beyond your application’s control, from trying to access a file that was moved, deleted or had its access permissions changed to I/O errors. If your application works with external information, it must be prepared to handle exceptions.
Python’s Exception Handling Keywords: try, except, else, and finally
Python’s exception handling takes a similar approach. It uses similar keywords to those in other popular programming languages — just with Python’s syntax, and an extra keyword for performing additional actions when an exception didn’t occur:
File-Related Exceptions
Here are the exceptions that you’re most likely to encounter when reading from or writing to files:
A File Exception-Handling Example
Here’s a quick exception handling example that shows all the keywords in action. Assume that the try block contains code that reads a specific file:
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