CODEWITHSUNDEEP
pythonpython-3.x
AmirM
AmirM

Reputation: 1139

How chain of `and` operators works in python?

In my program encountered with this:

>>> True and True and (3 or True)
3

>>> True and True and ('asd' or True)
'asd'

while I expected to get some boolean value depending on the result in brackets. So if I try comparisons like these (0 or True) or ('' or True) python will return True, which is clear because 0 and '' equivalent to False in comparisons.

Why doesn't python return boolean value by converting 3 and 'asd' into True?

Upvotes: 1

Views: 2409

Answers (1)

sheridp
sheridp

Reputation: 1406

From https://docs.python.org/3/library/stdtypes.html:

Important exception: the Boolean operations or and and always return one of their operands

The behavior can be most easily seen with:

>>> 3 and True
True

>>> True and 3
3

If you need to eliminate this behavior, wrap it in a bool:

>>> bool(True and 3)
True

See this question

As Reut Sharabani, answered, this behavior allows useful things like:

>>> my_list = []
>>> print (my_list or "no values")

Upvotes: 4

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