python字典值是列表时，字典值被异常修改!!

Question

 dict = {'a':[1,2,3,4,5],'b':2}
x = dict['a']
for i in range(5):
    x[i] = 0
print(dict['a'])

程序运行结果：

 [0, 0, 0, 0, 0]

怎么会这样？谁能帮忙解答一下

Answer 1

x赋值只是引用，可以用深拷贝，这样就不会修改原来的值了。改成如下即可：
import copy
dict = {'a':[1,2,3,4,5],'b':2}
x = copy.deepcopy(dict['a'])
for i in range(5):
x[i] = 0
print(dict['a'])