Python is = =

Before you distinguish between the IS and = = operators, the first thing to know about the three basic features of objects in Python is the ID (identity), Python type () (data type), and value. IS and = = are the object of comparative judgment, but the object comparison of the content is not the same. Here's a look at the exact difference.

Python compares two objects for equality, a total of two methods, in short, they differ as follows:

IS is to compare whether two references point to the same object (reference comparison).

= = is the comparison of two objects equal.

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>>> a = [1, 2, 3]>>> b = a>>> b is a # a的引用复制给b，他们在内存中其实是指向了用一个对象True >>> b == a # 当然，他们的值也是相等的True>>> b = a[:] # b通过a切片获得a的部分，这里的切片操作重新分配了对象，>>> b is a # 所以指向的不是同一个对象了False>>> b == a # 但他们的值还是相等的True

Implementation principle

Is compares whether the two are the same object, so the memory address (ID is the same) is compared.

= = is a value comparison. Immutable objects, such as INT,STR, that directly compare values

Python is = =