1.str >>>list 

str1 = "12345"
list1 = list(str1)
print list1

str2 = "123 sjhid dhi"
list2 = str2.split() #or list2 = str2.split(" ")
print list2

str3 = "www.google.com"
list3 = str3.split(".")
print list3

输出为：

['1', '2', '3', '4', '5']
['123', 'sjhid', 'dhi']
['www', 'google', 'com']

3.list >>>str

str4 = "".join(list3)
print str4
str5 = ".".join(list3)
print str5
str6 = " ".join(list3)
print str6

输出为：

wwwgooglecom
www.google.com
www google com

参考链接：

http://blog.csdn.net/cnmcsdn456/article/details/27830671

http://piziyin.blog.51cto.com/2391349/568426