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
list转tuple
list1=[1,2,3]
tup1=tuple(list1)
print(tup1)
print(list(tup1))