打包一个三字节的int [英] pack a three byte int
问题描述
Python不能表达三字节int的想法吗？
例如，在下面的工作示例中，我们可以以某种方式崩溃
struct.pack三次调用一次？
Can Python not express the idea of a three-byte int?
For instance, in the working example below, can we somehow collapse the
three calls of struct.pack into one?
>> import struct
skip = 0x123456; count = 0x80
cdb =''''
cdb + = struct.pack（''> B''，0x08）
cdb + = struct.pack（' '>我'，跳过）[ - 3：]
cdb + = struct.pack（''> BB''，伯爵，0）
打印'''' .join（[''％02X''％ord（xx）for xx in cdb]）
>>import struct
skip = 0x123456 ; count = 0x80
cdb = ''''
cdb += struct.pack(''>B'', 0x08)
cdb += struct.pack(''>I'', skip)[-3:]
cdb += struct.pack(''>BB'', count, 0)
print '' ''.join([''%02X'' % ord(xx) for xx in cdb])
08 12 34 56 80 00
08 12 34 56 80 00
>>>
>>>
我问，因为我正在尝试重构简洁的工作代码：
I ask because I''m trying to refactor working code that is concise:
>> cdb0 =''\ x08''''\ x12 \ x34 \ x56'''' \x80''''\'''
print''''。join（[''％02X''％ord（xx）for xx in cdb0]）
>>cdb0 = ''\x08'' ''\x12\x34\x56'' ''\x80'' ''\0''
print '' ''.join([''%02X'' % ord(xx) for xx in cdb0])
08 12 34 56 80 00
08 12 34 56 80 00
>>>
>>>
在此先感谢Pat LaVarre
Thanks in advance, Pat LaVarre
推荐答案
p.*******@ieee.org 写道：
Python不能表达三字节int的想法吗？
Can Python not express the idea of a three-byte int?
有点难以确定（修辞？）问题的含义。
可能的答案：
1.不像单字节结构代码那样简洁 - 因为你可能已经通过阅读手册确定了
...
2.不，但是当24位机器变得像在20世纪60年代那样受欢迎，随时提交增强请求:-)
It is a bit hard to determine what that (rhetorical?) question means.
Possible answers:
1. Not as concisely as a one-byte struct code -- as you presumably have
already determined by reading the manual ...
2. No, but when 24-bit machines become as popular as they were in the
1960s, feel free to submit an enhancement request :-)
>
例如，在下面的工作示例中，我们可以以某种方式将struct.pack的三次调用折叠成一个吗？
>
For instance, in the working example below, can we somehow collapse the
three calls of struct.pack into one?
> import struct
skip = 0x123456; count = 0x80
cdb =''''
cdb + = struct.pack（''> B''，0x08）
cdb + = struct.pack（' '>我'，跳过）[ - 3：]
cdb + = struct.pack（''> BB''，伯爵，0）
打印'''' .join（[''％02X''％ord（xx）for xx in cdb]）
>import struct
skip = 0x123456 ; count = 0x80
cdb = ''''
cdb += struct.pack(''>B'', 0x08)
cdb += struct.pack(''>I'', skip)[-3:]
cdb += struct.pack(''>BB'', count, 0)
print '' ''.join([''%02X'' % ord(xx) for xx in cdb])
08 12 34 56 80 00
08 12 34 56 80 00
>>
>>
您可以尝试在包装之前抛弃多余的部分而不是
之后：
| >>来自struct import pack
| >> skip = 0x123456; count = 0x80
| >> hi，lo = divmod（skip，0x10000）
| >> cdb = pack（"> BBHBB"，0x08，hi，lo，count，0）
| >>''''。join（[&x;％02X"％ord（x）for x in cdb]）
| ''08 12 34 56 80 00''
但为什么要这样做才能简化工作代码???
You could try throwing the superfluous bits away before packing instead
of after:
| >>from struct import pack
| >>skip = 0x123456; count = 0x80
| >> lo = divmod(skip, 0x10000)
| >>cdb = pack(">BBHBB", 0x08, lo, count, 0)
| >>'' ''.join(["%02X" % ord(x) for x in cdb])
| ''08 12 34 56 80 00''
but why do you want to do that to concise working code???
< br>
文章< 11 ********************** @ k70g2000cwa.googlegroups .com>，
p。******* @ ieee.org 写道：
In article <11**********************@k70g2000cwa.googlegroups .com>,
p.*******@ieee.org wrote:
Python可以不表达三字节int的想法吗？
例如，在下面的工作示例中，我们可以以某种方式崩溃
三struct.pack调用一个？
Can Python not express the idea of a three-byte int?
For instance, in the working example below, can we somehow collapse the
three calls of struct.pack into one?
> import struct
skip = 0x123456; count = 0x80
cdb =''''
cdb + = struct.pack（''> B''，0x08）
cdb + = struct.pack（' '>我'，跳过）[ - 3：]
cdb + = struct.pack（''> BB''，count，0）
>import struct
skip = 0x123456 ; count = 0x80
cdb = ''''
cdb += struct.pack(''>B'', 0x08)
cdb += struct.pack(''>I'', skip)[-3:]
cdb += struct.pack(''>BB'', count, 0)
为什么不是这样的：
skip + = struct.pack（"> L"，skip）[1：]
Dave
Why not something like this:
skip += struct.pack(">L", skip)[1:]
Dave
对不起，应该是：
cdb + = struct .pack（"> L"，skip）[1：]
Dave
Sorry, that should have been:
cdb += struct.pack(">L", skip)[1:]
Dave
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