将utf-16字符串传递给Windows函数 [英] Passing utf-16 string to a Windows function
问题描述
我有一个名为some.dll的Windows dll，具有以下功能：
I have a Windows dll called some.dll with the following function:
void some_func(TCHAR* input_string)
{
...
}
some_func期望指向utf的指针-16编码的字符串。
some_func expects a pointer to utf-16 encoded string.
运行以下python代码：
Running this python code:
from ctypes import *
some_string = "disco duck"
param_to_some_func = c_wchar_p(some_string.encode('utf-16')) # here exception!
some_dll = ctypes.WinDLL(some.dll)
some_dll.some_func(param_to_some_func)
失败，但出现以下异常：期望使用Unicode字符串或整数地址而不是字节实例
fails with exception "unicode string or integer address expected instead of bytes instance"
ctypes和ctypes文档.wintypes非常薄，我还没有找到将python字符串转换为Windows范围的char并将其传递给函数的方法。
The documentation for ctypes and ctypes.wintypes is very thin, and I have not found a way to convert a python string to a Windows wide char and pass it to a function.
推荐答案
根据 [Python 3.Docs ]：内置类型-文本序列类型-str （强调是我的）：
Python中的文本数据使用 str 对象或字符串。字符串是不可变的 Unicode代码点的顺序 >。
Textual data in Python is handled with str objects, or strings. Strings are immutable sequences of Unicode code points.
在 Win 上，它们是 UTF16 编码的。
因此， CTypes 和 Python 之间的对应关系（也可以通过检查之间的差异看到）：
So, the correspondence between CTypes and Python (also visible by checking the differences between):
- [Python 3.Docs]: ctypes - Fundamental data types
- [Python 2.Docs]: ctypes - Fundamental data types
╔═══════════════╦══════════════╦══════════════╗
║ CTypes ║ Python 3 ║ Python 2 ║
╠═══════════════╬══════════════╬══════════════╣
║ c_char_p ║ bytes ║ str ║
║ c_wchar_p ║ str ║ unicode ║
╚═══════════════╩══════════════╩══════════════╝
示例：
-
Python 3 ：
Python 3:
>>> import sys
>>> import ctypes as ct
>>>
>>> sys.version
'3.7.6 (tags/v3.7.6:43364a7ae0, Dec 19 2019, 00:42:30) [MSC v.1916 64 bit (AMD64)]'
>>>
>>> text_ascii = b"Dummy"
>>> text_unicode = "Dummy"
>>>
>>> ct.c_char_p(text_ascii)
c_char_p(2563882450144)
>>>
>>> ct.c_wchar_p(text_ascii)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: unicode string or integer address expected instead of bytes instance
>>>
>>> ct.c_char_p(text_unicode)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: bytes or integer address expected instead of str instance
>>>
>>> ct.c_wchar_p(text_unicode)
c_wchar_p(2563878400656)
Python 2 （请注意， str < => unicode 转换是自动执行的）：
Python 2 (note that str <=> unicode conversions are performed automatically):
>>> import sys
>>> import ctypes as ct
>>>
>>> sys.version
'2.7.17 (v2.7.17:c2f86d86e6, Oct 19 2019, 21:01:17) [MSC v.1500 64 bit (AMD64)]'
>>>
>>> text_ascii = "Dummy"
>>> text_unicode = u"Dummy"
>>>
>>> ct.c_char_p(text_ascii)
c_char_p('Dummy')
>>>
>>> ct.c_wchar_p(text_ascii)
c_wchar_p(u'Dummy')
>>>
>>> ct.c_char_p(text_unicode)
c_char_p('Dummy')
>>>
>>> ct.c_wchar_p(text_unicode)
c_wchar_p(u'Dummy')
返回您的情景：
>>> import ctypes as ct
>>>
>>> some_string = "disco duck"
>>>
>>> enc_utf16 = some_string.encode("utf16")
>>> enc_utf16
b'\xff\xfed\x00i\x00s\x00c\x00o\x00 \x00d\x00u\x00c\x00k\x00'
>>>
>>> type(some_string), type(enc_utf16)
(<class 'str'>, <class 'bytes'>)
>>>
>>> ct.c_wchar_p(some_string) # This is the right way
c_wchar_p(2508534214928)
>>>
>>> ct.c_wchar_p(enc_utf16)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: unicode string or integer address expected instead of bytes instance
作为旁注， TUNI 在定义的 _UNICODE 上有所不同（这是 typedef ）。检查 [MS.Docs]：通用-tchar.h 中的文本映射以获取更多详细信息。因此，根据 C 代码的编译标志， Python 代码也可能需要调整。
As a side note, TCHAR varies (it's a typedef) on _UNICODE (not) being defined. Check [MS.Docs]: Generic-Text Mappings in tchar.h for more details. So, depending on the C code compilation flags, the Python code might also need adjustments.
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