Python中input与raw_input 之间的比较
input和raw_input均可以接收输入，其差别如下所示：
#input假设用户输入的是合法的Python表达式
>>> name = input("what is your name?")
what is your name?ZJ
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<string>", line 1, in <module>
NameError: name 'ZJ' is not defined
#于是，必
