How is Boolean used in python?

Answer 1

Python has two constant objects, True and False and a bool() function. The bool() function simply casts its argument to one of the two Boolean objects.

All integral types (integers) will implicitly cast to True or False, such that the value zero is always False and non-zero is always True. Floating point types can also be implicitly cast (such that 0.0 is always False) however floating point values are approximations and should never be used implicitly. Instead, use comparison operators to perform an explicit cast:

if x == 0.0:

# do something

All the comparison operators return True or False, as do all the logic operators (and, or and not). However, it is never necessary to compare an expression with the True object:

if x == True:

The above can be reduced to the more efficient:

if x:

Where x cannot be implicitly cast to a Boolean constant, use the bool() function to perform an explicit cast:

if bool(x):

If you need to reverse the logic, you might use the following:

if bool (x) == False:

However, it is arguably more readable to use the not logic operator instead:

if not (bool (x)):

You can experiment with Boolean types through the bool function:

bool ('') # False

bool ('a string') # True

bool ([]) # False

bool ([1,2,3]) # True

bool (0) # False

bool (1) # True

bool (0.0) # False bool (42.0) # True

bool (False) # False

bool (True) # True

Note that the last two are redundant casts.