Python_Tips[6] -> is 和 == 的区别

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

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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，

x = [1, 2, 3]
y = [1, 2, 3]
z = x
print('x id is %d, y id is %d, z id is %d' % (id(x), id(y), id(z)))
# x id is 52275016, y id is 13096648, z id is 52275016

# is judge by id, == judge by value
print(x is y, x==y) # False, True
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

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