Python 101 (part 2): If Wishes Were Pythons - Time For Lunch (
Page 9 of 9 )
Python also allows you to combine multiple conditional
tests with the "and", "or" and "not" logical operators. If you consider the
following code
snippet,
if weekday == "Thursday":
if time == "12":
if place == "Italy":
lunch = "pasta"
you'll agree that is both complex and frightening. And so, in
addition to the comparison operators we've used so liberally thus far, Python
also provides the "and", "or" and "not" logical operators which allow you to
group conditional expressions together. The following table should make this
clearer.
Assume delta = 12, gamma = 12 and omega = 9
delta == gamma and delta > omega
True
delta == gamma and delta < omega
False
delta == gamma or delta < omega
True
delta > gamma or delta < omega
False
not delta
False
Given this knowledge, it's a simple matter to rewrite
the example above in terms of logical operators:
if weekday == "Thursday" and time == "12" and place == "Italy":
lunch = "pasta"
Simple and elegant, wot?
And that's about it for the
moment. You've learned a lot today - you now know how to manipulate strings and
numbers, obtain user input from the command line, and use the "if" family of
conditional statements to control the flow of your program.
In the next
article, I'll be discussing some of Python's loops, together with a close look
at another very useful and interesting Python data structure - the list. You
make sure that you come on back for that one!
