Unlike some other programming languages (such as Java, C/C++, JavaScript, PHP, etc.), Python does not have a "null" value. Instead, Python has a built-in "None
" constant that is semantically the same — i.e. they're both used to represent absence of value, or no value. Therefore, you can use None
to represent null values in Python.
For example, you can assign None
to a variable in the following way:
foo = None print(foo) # None
Similarly, you can assign None
to a function/method argument (to serve as a default value), like so:
def foo(arg = None): if arg is None: return 'empty' print(foo()) # 'empty'
None
can also be returned from a function:
def foo(): return None print(foo()) # None
When a function/method does not explicitly return a value, it is implicitly None
:
def foo(): pass print(foo()) # None
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