Having trouble using CTypes with a custom function

tkondal at gmail.com tkondal at gmail.com
Wed Oct 4 20:18:16 CEST 2006

Hi all.

I just started looking at Python's ctypes lib and I am having trouble
using it for a function.

For starters, here's my Python code:

from ctypes import*;
myStringDLL= cdll.LoadLibrary("myStringDLL.dll");

GetMyString = getattr(myStringDLL,
"?GetMyString@@YA_NAAV?$basic_string at DU?$char_traits at D@std@@V?$allocator at D@2@@std@@@Z")

strString =  create_string_buffer('\000' * 256);
GetMyString.restype = c_int;
GetMyString.argtypes = [c_char_p];

bResult = GetMyString (strSerialNumber);

print (bResult);
print (strSerialNumber);

#C++ Prototype of the function I want to call:
#bool GetMyString (string& stringParam) ;

I do not have access to the source code of this function so don't ask
me to try different things in C++.  This DLL is working fine.

The problem that I have is that print (strSerialNumber) does not seem
to print the correct string.  What I get is some garbage value of
unprintable characters.  Am I using this the correct way?


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