[英]How do I print a string from a struct?
So I have the string john
. 所以我有字符串
john
。 I pack it into a struct. 我将它打包成一个结构。 When I unpack it, how can I print
john
? 打开包装时,我怎么打印
john
? Currently it only prints j
. 目前它只打印
j
。 Same thing if I changed the string to Sammy
or other names with different lengths? 如果我将字符串更改为
Sammy
或其他不同长度的名称,同样的事情? I have 2 functions to pack and unpack the struct. 我有2个函数来打包和解压缩struct。 This what I don't need to worry about the lengths of the
first_name
's. 这就是我不需要担心
first_name
的长度。 The function can do it for me. 该功能可以为我做。
The structure is basically 结构基本上是
1
) 1
) john
) john
) My Code 我的守则
from struct import *
def make_struct(user_id, first_name):
return pack("is", user_id, first_name)
def deconstruct_struct(structure):
return unpack("is", structure)
packed = make_struct(1, "john")
unpacked = deconstruct_struct(packed)
print(unpacked[1])
Current output is: 目前的输出是:
j
You need to add the length of the string to the format string: 您需要将字符串的长度添加到格式字符串:
packed = pack("i4s", 1, "john")
unpacked = unpack("i4s", packed)
print(unpacked[1])
>> john
If you need a string of variable length -> packing and unpacking variable length array/string using the struct module in python 如果你需要一个可变长度的字符串 - > 使用python中的struct模块打包和解包变量长度数组/字符串
EDIT: 编辑:
Your solution can be extended like this: 您的解决方案可以像这样扩展:
from struct import *
def make_struct(user_id, first_name):
first_name_length = len(first_name)
fmt = "ii{}s".format(first_name_length) #generate format string with length of first_name
return pack(fmt, user_id, first_name_length, first_name) #add the length to the pack
def deconstruct_struct(structure):
user_id, first_name_length = unpack("ii", structure[:8]) #extract only userid and length from the pack
fmt = "ii{}s".format(first_name_length) #generate the format string like above
#return unpack(fmt, structure) #this would return a (user_id, length of first name, first_name) tuple
return (user_id, unpack(fmt, structure)[2]) #this way, we return only the (user_id, first_name) tuple
packed = make_struct(1, "john")
unpacked = deconstruct_struct(packed)
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