Why does ctypes find my dll but not my function?

Question

I am trying to rewrite an 32bit Matlab-script in Python. For this I need to include a dll, which I am trying to do with ctypes. Somehow the Python script does find the dll, but not the function I am searching for. I know the name of the function, because I have got the separate header-file and already used that function in my Matlab-script.

from ctypes import cdll

xxx = cdll.LoadLibrary('C:\\Users\\Marco\\Software\\Python\\xxxdllio.dll')
res=xxx.xxxdll_set_comm()

The terminal says:

AttributeError: function 'xxxdll_set_comm' not found

The following is a clip out of the dlls header-file:

*// usage: xxxdll_set_comm(hex_num, func , data);

I am fairly new to Python, so have no idea, why my Matlab-script finds this function and my Python-script not.

Answer 1

Thanks alot tdelaney, after a couple of hours now, i managed to get it running, because of your tip. I installed a few older versions of visual studios but never managed to find dumpbin. If you download Visual Code 2017 Professional Edition with the C++ MSVC Buildtools, you can find under the following location dumpbin.exe

C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.10.25017\bin\HostX86\x86\dumpbin.exe

After opening the Developer Command Prompt and changing the directory to the dlls location, i got the following output:

 Dump of file xxxdllio.dll

File Type: DLL



 Section contains the following exports for xxxdllio.dll

00000000 characteristics
       0 time date stamp
    0.00 version
       1 ordinal base
      13 number of functions
      13 number of names

ordinal hint RVA      name

      1    0 000088D0 @__lockDebuggerData$qv
      2    1 000088F8 @__unlockDebuggerData$qv
      3    2 000034CA @xxxiodll_scan_get$qpus
      4    3 000034F2 @xxxiodll_scan_get_long$qpui
      5    4 00008205 @xxxiodll_set_comm$qiii
      6    5 00008243 @xxxiodll_set_comm_ptr$qiipv
      7    6 00008235 @xxxiodll_var_get_float$qui
      8    7 000147F0 __DebuggerHookData
      9    8 000034CA xxxiodll_scan_get
     10    9 000034F2 xxxiodll_scan_get_long
     11    A 00008205 xxxiodll_set_comm
     12    B 00008243 xxxiodll_set_comm_ptr
     13    C 00008235 xxxiodll_var_get_float

So it looks like i was missing an "io" in my functions name.