Python's None: Null in Python (Overview)

what is difference between null and blank ?

By “null” do you mean “None”? By “blank” I assume you mean ‘’ (empty string).

The main difference between None and ‘’ is their types: The type of None is NoneType and the type of ‘’ is str (string).

type(None) <class ‘NoneType’> type(‘’) <class ‘str’>

Another difference is how they’re used. Both are “Falsy” (meaning in conditional expressions, they evaluate to False).

‘Yes’ if None else ‘No’ ‘No’ ‘Yes’ if ‘’ else ‘No’ ‘No’

not None True not ‘’ True

But they format and concatenate differently.

’{}’.format(None) ‘None’ ‘{}’.format(‘’) ‘’

None + ‘more’ Traceback (most recent call last): File “<input>”, line 1, in <module> TypeError: unsupported operand type(s) for +: ‘NoneType’ and ‘str’ ‘’ + ‘more’ ‘more’

Wow, I really should've previewed that before I posted… ;-)

Here’s what I meant to write:

By “null” do you mean “None”?

By “blank” I assume you mean ‘’ (empty string).

The main difference between None and ‘’ is their types: The type of None is NoneType and the type of ‘’ is str (string).

>>> type(None)
<class ‘NoneType’>  
>>> type(‘’)  
<class ‘str’>  

Another difference is how they’re used. Both are “Falsy” (meaning in conditional expressions, they evaluate to False).

>>> ‘Yes’ if None else ‘No’  
‘No’  
>>> ‘Yes’ if ‘’ else ‘No’  
‘No’

>>> not None
True
>>> not ‘’
True

But they format and concatenate differently.

>>> ’{}’.format(None)
‘None’
>>> ‘{}’.format(‘’)
‘’

>>> None + ‘more’
Traceback (most recent call last): File “<input>”, line 1, in <module> TypeError: unsupported operand type(s) for +: ‘NoneType’ and ‘str’
>>> ‘’ + ‘more’
‘more’

@kemjones Thanks for the update.

>>> None + ‘more’
Traceback (most recent call last): File “<input>”, line 1, in <module> TypeError: unsupported operand type(s) for +: ‘NoneType’ and ‘str’
>>> ‘’ + ‘more’
‘more’

this is perfect example. Thanks.

@manu

As Christian explained in his video, there’s no “null” in Python, but a lot of other programming languages use it to denote missing values.

None is a special value in Python used to indicate a lack of something. For example, functions that don’t return anything, in fact, return None implicitly:

>>> print(exec(''))
None

The word “blank” refers to empty strings, which have no characters:

>>> empty_string = ""
>>> len(empty_string)
0

Note that an empty string exists in memory and can tell you its length, which is zero, so it isn’t the same as no string whatsoever:

>>> empty_string = ""
>>> empty_string is None
False

@Bartosz Zaczyński Thanks for the update.