Python_Tips[6] -> is 和 == 的区别

is和==的区别 / Difference between is and ==

对于Python的对象来说，具有id/type/value三种特性，而在判断两个相等的is和==中，分别是对对象的id和value进行判断，以下例子可以看出两者的不同之处，

1 x = [1, 2, 3]
2 y = [1, 2, 3]
3 z = x
4 print('x id is %d, y id is %d, z id is %d' % (id(x), id(y), id(z)))
5 # x id is 52275016, y id is 13096648, z id is 52275016
6 
7 # is judge by id, == judge by value
8 print(x is y, x==y) # False, True
9 print(x is z, x==z) # True, True

从查看的结果来看，x和y的值相同，但是id却不同，而x和z的值相同，也就是两者指向了同一个对象，分别将y和z与x进行等价比较，结果中可以看出，id相同的x和z的is语句判断成立，而id不同但是值相同的x和y则不成立。

参考链接

http://blog.csdn.net/imzoer/article/details/8637408