python中二进制数据的长度 [英] Length of binary data in python

问题描述

我正在使用Python。我正在尝试确定二进制数据集中字节的正确长度。

I am using Python. I am trying to determine the correct length of bytes in a binary set of data.

如果我为变量分配了二进制数据...

If I assign a variable the binary data...

x = "aabb".decode("hex")

与

x = b'aabb'

如果是的话，如何获得多少字节？ （应该为2个字节）

And if so, how do you get how many bytes that is? (It should be 2 bytes)

当我尝试：

len(x)

虽然我得到了4个而不是2个...

I get 4 instead of 2 though...

我担心x会变成字符串或其他我不理解的东西，因为数据类型在Python中是如此不稳定...

I am worried that x is turned into a string or something else I don't understand because the data types are so fluid in Python...

推荐答案

二进制数据的长度仅为 len ，类型为 str 在Python-2.x中（或 bytes 在Python-3.x中）。但是，您的对象'aabb'不包含两个字节0xaa和0xbb，而是包含4个字节，分别对应ASCII'a'和'b'字符：

The length of binary data is just the len, and the type is str in Python-2.x (or bytes in Python-3.x). However, your object 'aabb' does not contain the two bytes 0xaa and 0xbb, rather it contains 4 bytes corresponding with ASCII 'a' and 'b' characters:

>>> bytearray([0x61, 0x61, 0x62, 0x62])
bytearray(b'aabb')
>>> bytearray([0x61, 0x61, 0x62, 0x62]) == 'aabb'
True

这可能实际上是您实际上在寻找的等效项：

This is probably the equivalence you were actually looking for:

>>> 'aabb'.decode('hex') == b'\xaa\xbb' 
True

以下各项均相等（且长度 2 ）：

The following items are all equal (and length 2):

>>> s1 = 'aabb'.decode('hex')
>>> s2 = b'\xaa\xbb'
>>> s3 = bytearray([0xaa, 0xbb])
>>> s4 = bytearray([170, 187])
>>> s1 == s2 == s3 == s4
True

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