Python built-in functions (6) -- bool, python built-in function bool

Python built-in functions (6) -- bool, python built-in function bool

English document:

Class bool([ X])

Return a Boolean value, I. e. oneTrueOrFalse.XIs converted using the standard truth testing procedure. IfXIs false or omitted, this returnsFalse; Otherwise it returnsTrue.boolClass is a subclassint(See Numeric Types-int, float, complex). It cannot be subclassed further. Its only instances areFalseAndTrue(See Boolean Values ).

Note:

1. boolean values that return True or False

2. If the parameter is set to the default value, False is returned.

>>> Bool () # unspecified parameter False

3. Use a standard logical test expression for parameter conversion

3.1 When a boolean type is passed in, the return value is based on the original value.

>>> bool(True)True>>> bool(False)False

3.2 If a null string is input, False is returned; otherwise, True is returned.

>>> bool('')False>>> bool('0')True

3.3 When a value is input, False is returned for the value 0; otherwise, True is returned.

>>> bool(0)False>>> bool(1)True>>> bool(-1.0)True

3.4 if the number of elements is null when objects such as tuples, lists, and dictionaries are input, False is returned; otherwise, True is returned.

>>> Bool () # Empty tuples False >>> bool (0,) # non-empty tuples True >>> bool ([]) # Empty list False >>> bool ([0]) # non-empty list True >>> bool ({}) # empty dictionary False >>> bool ({'K ': 'V'}) # non-empty dictionary True