Python Evaluate Booleans
Evaluate Values
The bool() function allows you to evaluate
any value, and give you
True or False
in return,
Most Values are True
Almost any value is evaluated to True if it
has some sort of content.
Any string is True, except empty strings.
Any number is True, except
0.
Any list, tuple, set, and dictionary are True, except
empty ones.
Example
The following will return True:
bool("abc")
bool(123)
bool(["apple", "cherry", "banana"])
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Some Values are False
In fact, there are not many values that evaluates to
False, except empty values, such as (),
[], {},
"", the number
0, and the value None.
And of course the value False evaluates to
False.
Example
The following will return False:
bool(False)
bool(None)
bool(0)
bool("")
bool(())
bool([])
bool({})
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One more value, or object in this case, evaluates to
False, and that is if you have an object that
is made from a class with a __len__ function that returns
0 or
False:
Example
class myclass():
def __len__(self):
return 0
myobj = myclass()
print(bool(myobj))
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