list（string）如何将字符串拆分为python中的字符数组？

Question

a = "Stack"
aList = list(a)

This gives me an array like this ['S','t',a','c','k']

I want to know how this list(string) function works!

Answer 1

A string is an iterable type. For example, if you do this:

for c in 'string':
    print c

You get

s
t
r
i
n
g

So passing a string to list just iterates over the characters in the string, and places each one in the list.

Answer 2

String is iterable in python because you can do

>>> for ch in "abc":
...         print ch
...
a
b
c
>>>

and if you take a look at list class construtor using help("list") in your python interpreter

class list(object)
 |  list() -> new empty list
 |  list(iterable) -> new list initialized from iterable's items

So, list("hello") returns a new list initialized.

>>> x = list("hello")
>>> type(x)
<type 'list'>
>>>

Answer 3

This works because str implements __iter__ , which allows iter(obj) to be called on the object. For str , the implementation returns character by character.

Answer 4

Most of the work is actually being done by the string. You are actually using the constructor of the list type. In Python, we are usually not so concerned with what things are, but rather with what they can do.

What a string can do is it can give you (eg for the purpose of using a for loop) its characters (actually, length-1 substrings; there isn't a separate character type) one at a time. The list constructor expects any object that can do this, and constructs a list that contains the elements thus provided.