[Tutor] Why isn't my simple if elif script not working?

[Alexandre Zani]

On Tue, Jul 17, 2012 at 10:21 PM, Andre' Walker-Loud
<walksloud at gmail.com> wrote:
> Hi Santosh,
>
> On Jul 17, 2012, at 10:09 PM, Santosh Kumar wrote:
>
>> Here is my script:
>>
>> name = raw_input("What's your name? ")
>>
>> if name == "Santosh":
>>    print "Hey!! I have the same name."
>> elif name == "John Cleese" or "Michael Palin":
>>    print "I have no preference about your name. Really!!"
>> else:
>>    print "You have a nice name."
>>
>>
>> The if part works well. The elif part works well too. The problem is
>> even if you enter strings other than "Santosh", "John Cleese" and
>> "Michael Palin" you still get the print from elif part, not from else
>> part.
>
> you just have to be careful with the multiple boolean line in the elif.  You can use either
>
> elif name == ("John Cleese" or "Michael Palin"):

That won't work.

>>> "John Cleese" == ("John Cleese" or "Michael Palin")
True
>>> "Michael Palin" == ("John Cleese" or "Michael Palin")
False
>>> ("John Cleese" or "Michael Palin")
'John Cleese'

Python will look at the expression ("John Cleese" or "Michael Palin")
since bool("John Cleese") is True, the expression immediately
evaluates to "John Cleese" and the elif clause becomes equivalent to
name == "John Cleese"

>
> or
>
> elif name == "John Cleese" or name == "Michael Palin":
>
>
> With your elif line, it is asking "does name ==  John Cleese" or "Michael Palin", and so if the name is not John Cleese, then I believe it prints "Michael Palin" while reporting True, so satisfying the elif clause.
>
>
> Cheers,
>
> Andre
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