join用来连接字符串，split恰好相反，拆分字符串的。

不用多解释，看完代码，其意自现了。

复制代码 代码如下:

>>>li = ['my','name','is','bob']

>>>' '.join(li)

'my name is bob'

>>>s = '_'.join(li)

>>>s

'my_name_is_bob'

>>>s.split('_')

['my', 'name', 'is', 'bob']

其join和split的英文版解释如下：

join(...)

S.join(sequence) -> string

Return a string which is the concatenation of the strings in the

sequence. The separator between elements is S.

split(...)

S.split([sep [,maxsplit]]) -> list of strings

Return a list of the words in the string S, using sep as the

delimiter string. If maxsplit is given, at most maxsplit

splits are done. If sep is not specified or is None, any

whitespace string is a separator and empty strings are removed

from the result.