[Tutor] The Boolean operator "and"
Jeff Shannon
jeff at ccvcorp.com
Fri Aug 6 20:39:59 CEST 2004
Dick Moores wrote:
> I have a question about one sentence in the fine Python book I'm
> presently studying, Practical Python, by Magnus Lie Hetland (Apress).
> The sentence is "Actually, if x is false, it returns x--otherwise it
> returns y." This sentence is in the paragraph on p. 109 that begins,
The key here is that there's a difference between being false, and
being False. [], {}, 0.0, and 0 are all 'false' as well, and if x is
one of those things, you'll get that rather than the boolean object False.
>>> x = []
>>> y = [1]
>>>
>>> x and y
[]
>>> x or y
[1]
>>>
If you're using this in a boolean context (i.e. an if statement), then
the effect is the same as if it were False, but in other contexts the
distinction can be important.
Jeff Shannon
Technician/Programmer
Credit International
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