这个python代码调用一个dll（在LabVIEW中创建），它返回作为参数传递的字符串的大小。每次我尝试传递不同大小的字符串时，它返回的大小为“1”。我尝试用不同的编程语言（如C，LabVIEW）调用dll，它运行正常。
下载dll文件的链接：https://drive.google.com/open?id=1pnYI6-SfUY3Cn6EeD4mWUO6dlEBH3DmN
import ctypes
from ctypes import windll, cdll,\
c_wchar, c_size_t, c_ulonglong, c_wchar_p, c_void_p,\
sizeof,\
WinError
try:
dllhandle = ctypes.CDLL("Strlen.dll")
print("Library Loaded")
except Exception as e:
print("Can't open DLL:",e)
dllhandle.Strlen.argtypes = [ctypes.c_wchar_p]
dllhandle.Strlen.restype = ctypes.c_int32
data = "Hello"
data_ptr = ctypes.c_wchar_p(data)
print("Data Pointer:",data_ptr)
length = dllhandle.Strlen(data_ptr)
print("Data:",data)
print("String Length:",length)
任何人都可以帮我解决这个问题吗？。提前谢谢。
笔记：
我的猜测是正确的：函数需要一个char *（8位），而wchar\t *是16位。
测试代码（code.py）：
#!/usr/bin/env python3
import sys
from ctypes import CDLL,\
c_int, c_char_p, c_wchar_p
WORDS = [
"",
"a",
"q z",
"asd\n",
"12345",
"qwertyuiop",
]
if __name__ == "__main__":
print("Python {:s} on {:s}\n".format(sys.version, sys.platform))
strlen_dll = CDLL("Strlen")
strlen_func = strlen_dll.Strlen
strlen_func.restype = c_int
for word in WORDS:
print("{:s}:\n len: {:d}".format(repr(word), len(word)))
strlen_func.argtypes = [c_char_p]
print(" Strlen.Strlen(c_char_p): {:d}".format(strlen_func(word.encode())))
strlen_func.argtypes = [c_wchar_p]
print(" Strlen.Strlen(c_wchar_p): {:d}".format(strlen_func(word)))
输出：
(py35x64_test) E:\Work\Dev\StackOverflow\q049030000>"e:\Work\Dev\VEnvs\py35x64_test\Scripts\python.exe" code.py Python 3.5.4 (v3.5.4:3f56838, Aug 8 2017, 02:17:05) [MSC v.1900 64 bit (AMD64)] on win32 '': len: 0 Strlen.Strlen(c_char_p): 0 Strlen.Strlen(c_wchar_p): 0 'a': len: 1 Strlen.Strlen(c_char_p): 1 Strlen.Strlen(c_wchar_p): 1 'q z': len: 3 Strlen.Strlen(c_char_p): 3 Strlen.Strlen(c_wchar_p): 1 'asd\n': len: 4 Strlen.Strlen(c_char_p): 4 Strlen.Strlen(c_wchar_p): 1 '12345': len: 5 Strlen.Strlen(c_char_p): 5 Strlen.Strlen(c_wchar_p): 1 'qwertyuiop': len: 10 Strlen.Strlen(c_char_p): 10 Strlen.Strlen(c_wchar_p): 1
说明：
unsigned short）。根据[MS.Docs]: Working with Strings
Windows表示使用UTF-16编码的Unicode字符，其中每个字符都编码为16位值。