Python Evaluate Booleans
Evaluate Values
The bool()
function allows you to evaluate
any value, and give you
True
or False
in return,
ExampleGet your own Python Server
Evaluate a string and a number:
print(bool("Hello"))
print(bool(15))
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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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