Python 2.7 quick reference

The purpose of the if construct is to execute some statements only when certain conditions are true.

Here is the most general form of an if construct:

if E0:
    B0
elif E1:
    B1
elif ...:
    ...
else:
    Bf

In words, this construct means:

An if construct may have zero or more elif clauses. The else clause is also optional.

Examples:

>>> for i in range(5):
...     if i == 0:
...         print "i is zero",
...     elif i == 1:
...         print "it's one",
...     elif i == 2:
...         print "it's two",
...     else:
...         print "many",
...     print i
... 
i is zero 0
it's one 1
it's two 2
many 3
many 4
>>> if 2 > 3: print "Huh?"
... 
>>> if 2 > 3: print "Huh?"
... else: print "Oh, good."
... 
Oh, good.
>>> if 2 > 3: print "Huh?"
... elif 2 == 2: print "Oh."
... 
Oh.