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。 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.