列表与字符串转换

>>> s = 'spam'
>>> t = list(s)
>>> t
['s', 'p', 'a', 'm']

Because list is the name of a built-in function, you should avoid using it as a variable

name. I also avoid l because it looks too much like 1. So that’s why I use t.
The list function breaks a string into individual letters. If you want to break a string into

words, you can use the split method:

>>> s = 'pining for the fjords'
>>> t = s.split()
>>> t
['pining', 'for', 'the', 'fjords']

An optional argument called a delimiter specifies which characters to use as word bound- aries. The following example uses a hyphen as a delimiter:

>>> s = 'spam-spam-spam'
>>> delimiter = '-'
>>> t = s.split(delimiter)
>>> t

['spam', 'spam', 'spam']
join is the inverse of split. It takes a list of strings and concatenates the elements. join is

a string method, so you have to invoke it on the delimiter and pass the list as a parameter:

>>> t = ['pining', 'for', 'the', 'fjords']
>>> delimiter = ' '
>>> s = delimiter.join(t)
>>> s

'pining for the fjords'
In this case the delimiter is a space character, so join puts a space between words. To

concatenate strings without spaces, you can use the empty string, '', as a delimiter.