Python built-in functions (6)--bool

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class bool ([ x])

Return a Boolean value, i.e. one of True or False . x is converted using the standard Truth testing procedure. If x is False or omitted, this returns False ; otherwise it returns True . boolThe class is a subclass of int (see Numeric Types-int, float, complex). It cannot be subclassed further. Its is only instances is and False True (see Boolean Values).

Description

1. A Boolean value that returns a value of TRUE or False

2. Returns False if the parameter is default

# parameter not passed in False

3. Parameter conversions use standard logic test expressions

3.1 When you pass in a Boolean type, return by the original value

>>> bool (true) True>>> bool (false) False

3.2 An empty string returns False if the string is passed in, otherwise true

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

3.3 When the value is passed in, 0 returns false, otherwise true

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

3.4 When passing in tuples, lists, dictionaries, and other objects, the number of elements is null returns FALSE, otherwise true

>>> bool (())#Empty tupleFalse>>> bool ((0,))#non-null tupleTrue>>> bool ([])#Empty listFalse>>> bool ([0])#non-empty listTrue>>> bool ({})#Empty DictionaryFalse>>> BOOL ({'k':'v'})#non-empty dictionariesTrue

Python built-in functions (6)--bool