Understand where integer objects are stored in Python

The storage locations of integer objects in Python are different. Some are pre-allocated memory and are always stored in memory, while others open up space when used.

The reason for saying this, You can take a look at the following code:

a = 5
b = 5
a is b # True
a = 500
b = 500
a is b # False

As can be seen from the above code, the integer type 5 always exists, but the integer type 500 does not always exist.

So which integers have pre-allocated memory addresses?

a, b, c = 0, 0, 0
i = 0
while a is b:
    i += 1
    a, b = int(str(i)), int(str(i))
else:
    print(i) # 打印 257

As we know from the above, non-negative integers less than or equal to 256 (2**8) are always stored (that is to say, their memory addresses are allocated in advance and do not need to be allocated later)

a = -1
b = -1
a is b # False

​

And negative numbers will not be opened in advance.