Python 101 (part 2): If Wishes Were Pythons - Cookie-Cutter Code (
Page 8 of 9 )
The "if-else"
construct certainly offers a smidgen more flexibility than the basic "if"
construct, but still limits you to only two possible courses of action. If your
Python script needs to be capable of handling more than two possibilities, you
should reach for the "if-elif-else" construct, which is a happy combination of
the two constructs you've just been reading about.
if first condition is true:
do this!
elif second condition is true:
do this!
elif third condition is true:
do this!
... and so on ...
else:
do this!
There's one important point to be noted here - as soon as one
of the "if" statements within the block is found to be true, Python will execute
the corresponding code, skip the remaining "if" statements in the block, and
jump immediately to the lines following the entire "if-elif-else"
block.
Take a look at it in action:
#!/usr/bin/python
print "Welcome to the Amazing Fortune Cookie Generator";
# get input
day = raw_input("Pick a day, any day: ");
# check day and assign fortune
if day == "Monday":
fortune = "Never make anything simple and efficient when a way can
be found to make it complex and wonderful."
elif day == "Tuesday":
fortune = "Life is a game of bridge -- and you've just been
finessed."
elif day == "Wednesday":
fortune = "What sane person could live in this world and not be
crazy?"
elif day == "Thursday":
fortune = "Don't get mad, get interest."
elif day == "Friday":
fortune = "Just go with the flow control, roll with the crunches,
and, when you get a prompt, type like hell."
else:
fortune = "Sorry, closed on the weekend"
# output
print fortune
You'll notice that in this case, I've used the raw_input()
function instead of the regular input() function. The difference between the two
is minor: raw_input() stores user input as is, while input() attempts to convert
user input into a Python expression.
Since Python does not support PHP-
or JSP-style "switch/case" conditional statements, the "if-elif-else" construct
is the only way to route program control to multiple code blocks.
