HomePython Page 2 - Python 101 (part 5): Snake Oil For The Soul
Air In A Bottle - Python
Now that you know how to create and use Python's tuples, listsand dictionaries, it's time to get your hands dirty. In this article, findout how to read from, and write to, files on the filesystem with built-inPython methods, and also take a look at some of the new features availablein Python 2.x.
Like all widely-used programming languages, Python has the very usefulability to read data from, and write data to, files on your system. Itaccomplishes this via "file handles" - a programming construct that allowsPython scripts to communicate with data structures like files, directoriesand other Python scripts.
For my first example, I'll assume that I have a text file called"snakeoil.txt", containing the following commercial:
After years of research, scientists at AB Labs have come up with a radical
new product, once that promises to improve the quality of life for humans
and animals everywhere.
We call it Air In A Bottle(tm), and we firmly consider it to be one of our
best inventions ever.
Carry it around with you (the bottle is titanium, the same material used in
rocket ships, and the air is, well, air) and inhale from it whenever you
need some air. Or give it to your friends as a present (after all, they
need air too!)
Air In A Bottle(tm). Get some today!
Now, in order to read this data into a Python program, I need to open thefile and assign it a file handle - this file handle can then be used tointeract with the data.
Python 1.5.2 (#1, Aug 25 2000, 09:33:37) [GCC 2.96 20000731
(experimental)] on
linux-i386
Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
>>> data = open("snakeoil.txt")
>>> data.read()
'After years of research, scientists at AB Labs have come up with a radical
new
product, once that promises to improve the quality of life for humans and
animals everywhere.\012 \012We call it Air In A Bottle(tm), and we firmly
consider it to be one of our best inventions ever.\012\012Carry it around
with you (the bottle is titanium, the same material used in rocket ships,
and the air is, well, air) and inhale from it whenever you need some air.
Or give it to your friends as a present (after all, they need air
too!)\012\012Air In A Bottle(tm). Get some
today!\012'
>>> data.close()
>>>
In this case, I've first used the open() function to open the file"snakeoil.txt" and assign it to the file handle "data". Next, I've used theread() function to read everything in the file, and the close() function toclose the handle after I'm done.
Since this is the command-line interpreter, a read() call will display thecontents of the file on the console, complete with line breaks (in caseyou're wondering, that's what \012 is.) The read() function reads theentire file into a single string.
Python 
