How do I use a Boolean in Python?
checker = None
if some_decision:
checker = True
if checker:
# some stuff
[Edit]
For more information: http://docs.python.org/library/functions.html#bool
Your code works too, since 1
is converted to True
when necessary.
Actually Python didn't have a boolean type for a long time (as in old C), and some programmers still use integers instead of booleans.
The boolean builtins are capitalized: True
and False
.
Note also that you can do checker = bool(some_decision)
as a bit of shorthand -- bool
will only ever return True
or False
.
It's good to know for future reference that classes defining __nonzero__
or __len__
will be True
or False
depending on the result of those functions, but virtually every other object's boolean result will be True
(except for the None
object, empty sequences, and numeric zeros).
True
... and False
obviously.
Otherwise, None
evaluates to False, as does the integer 0
and also the float 0.0
(although I wouldn't use floats like that).
Also, empty lists []
, empty tuplets ()
, and empty strings ''
or ""
evaluate to False.
Try it yourself with the function bool()
:
bool([])
bool(['a value'])
bool('')
bool('A string')
bool(True) # ;-)
bool(False)
bool(0)
bool(None)
bool(0.0)
bool(1)
etc..