python32版本,struct.error: argument for 's' must be a bytes object - 小众知识

python32版本,struct.error: argument for 's' must be a bytes object

2013年01月27日 14:18:05 苏内容
  标签: Python
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@for ever 2012-06-25


在python32版本下面,下面的代码:


[python] view plaincopy
msg = pack(">H%ds" % len(reason), code, reason) 

执行后出现如下的错误:
[plain] view plaincopy
struct.error: argument for 's' must be a bytes object 

做如下修改,错误解决:
[python] view plaincopy
msg = pack(">H%ds" % len(reason), code, reason.encode('utf-8')) 
[python] view plaincopy
 
关于struct.pack函数,参数个数是无限的。第一个参数定义打包格式,
剩余的所有参数都是要打包的内容。
第一个格式参数具体写法如下:
Format c Type
Python Note
x pad byte no value 
c char string of length 1 
b signedchar integer 
B unsignedchar
integer 
? _Bool bool (1)
h short integer 
H unsignedshort
integer 
i int integer 
I unsignedint
integer or long 
l long integer 
L unsignedlong
long 
q longlong long (2)
Q unsignedlonglong
long (2)
f float float 
d double float 
s char[] string 
p char[] string 
P void* long 
此外,还包含相应的大/小端设置(如果忽略该设置,默认<):
@ native native
= native standard
< little-endian
standard
> big-endian standard
! network (= big-endian)
standard


@forandever 2012-6-25


 


3
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I am attempting to execute the code:

    values = (1, 'ab', 2.7)   
    s.struct.Struct('I 2s f')
    packed = s.pack(*values)
But I keep getting the error:

    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    struct.error: argument for 's' must be a bytes object
Why? How do I fix this?


With Python 3, 'ab' isn't a bytes object, what was called a str on Python 2, it's unicode. You need to use:

values = (1, b'ab', 2.7)
which tells Python that 'ab' is a byte literal. See PEP 3112 for more info.

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answered Apr 10 '12 at 3:09

agf
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This answer should be marked as THE answer to the question. –  rbaleksandar Sep 29 '13 at 11:33

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