Unexpected blank lines in Python strings

Question

Pay attention to the following interactive session:

In [1]: s = 'emptiness'

In [2]: s.replace('', '*')
Out[2]: '*e*m*p*t*i*n*e*s*s*'

In [3]: s.count('')
Out[3]: 10

I discovered this today and it is a bit confusing and surprising to me.

I like to learn things like Python, but it looks like this might lead to some pretty confusing errors. For example, if an empty string was passed as a variable and just turned out to be an empty string, you might get some unexpected consequences. The behavior also seems a little inconsistent because, based on the interactive session above, I would have thought that the following would lead to a list of all the characters in the string (similar to JavaScript behavior). Instead, you get an error message:

In [4]: s.split('')
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-4-c31bd2432bc1> in <module>()
----> 1 s.split('')

ValueError: empty separator

In addition, this leads to some seemingly contradictory behavior with str.endswith()and str.startswith():

In [5]: s.endswith('')
Out[5]: True

In [6]: s.endswith('s')
Out[6]: True

In [7]: s.startswith('')
Out[7]: True

In [8]: s.startswith('e')
Out[8]: True

, .

: ? , str ? - - / , .

Answer 1

Python , . , python , , , . :

>>>'a'.count('')
2
>>>'aa'.count('')
3
>>>'string'.count('')
7

So 'a' ''+'a'+'', 'aa' ''+'a'+''+'a'+''.

'a'.startswith(''), , 'a' . 'a'.endswith(''). , 'a'.startswith('a'), .