python中二进制数据的长度
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Length of binary data in python
提问by Matthew
I am using Python. I am trying to determine the correct length of bytes in a binary set of data.
我正在使用 Python。我正在尝试确定二进制数据集中的正确字节长度。
If I assign a variable the binary data...
如果我分配一个变量二进制数据......
x = "aabb".decode("hex")
is that the same as
是不是一样
x = b'aabb'
And if so, how do you get how many bytes that is? (It should be 2 bytes)
如果是这样，您如何获得多少字节？（应该是2个字节）
When I try:
当我尝试：
len(x)
I get 4 instead of 2 though...
不过我得到 4 而不是 2...
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...
我担心 x 变成字符串或其他我不明白的东西，因为 Python 中的数据类型是如此流畅......
回答by wim
The length of binary data is just the len, and the type is strin Python-2.x (or bytesin 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:
二进制数据的长度为len，类型str在 Python-2.x（或bytesPython-3.x）中。但是，您的对象'aabb'不包含两个字节 0xaa 和 0xbb，而是包含与 ASCII 'a' 和 'b' 字符对应的 4 个字节：
>>> bytearray([0x61, 0x61, 0x62, 0x62])
bytearray(b'aabb')
>>> bytearray([0x61, 0x61, 0x62, 0x62]) == 'aabb'
True
This is probably the equivalence you were actuallylooking for:
这可能是您实际寻找的等效项：
>>> 'aabb'.decode('hex') == b'\xaa\xbb'
True
The following items are all equal (and length 2):
以下项目都是相等的（和 length 2）：
>>> s1 = 'aabb'.decode('hex')
>>> s2 = b'\xaa\xbb'
>>> s3 = bytearray([0xaa, 0xbb])
>>> s4 = bytearray([170, 187])
>>> s1 == s2 == s3 == s4
True
