Loading dll using Python Ctypes -

i've looked @ example given here ctypes - beginner , followed same steps different bit of c code. i've built .dll , .lib using c code given here: http://wolfprojects.altervista.org/articles/dll-in-c-for-python/

  //test.c __declspec(dllexport) int sum(int a, int b) {     return + b; } 

in wrapper.py have this:

import ctypes  testlib = ctypes.cdll("c:\\users\\xyz\\documents\\python\\test.dll") 

when run script error:

self._handle = _dlopen(self._name, mode)

oserror: [winerror 193] %1 not valid win32 application

if use

testlib = ctypes.libraryloader("c:\\users\\xyz\\documents\\python\\test.dll") 

then don't error on running script. if try this:

testlib.sum(3,4) 

i error:

dll = self._dlltype(name)

typeerror: 'str' object not callable

the dll , .py in same folder. can me understand what's going on here. i've spent hours trying figure out, have hit wall. thanks.

make sure compiler , version of python both 32-bit or both 64-bit. can't mix, cause of oserror: [winerror 193] %1 not valid win32 application.

next, make sure compile c program , not c++. that's cause of name mangling mention in answer.

example (note compiler x86 not x64:

c:\>cl /ld /w4 test.c microsoft (r) c/c++ optimizing compiler version 17.00.61030 x86 copyright (c) microsoft corporation.  rights reserved.  test.c microsoft (r) incremental linker version 11.00.61030.0 copyright (c) microsoft corporation.  rights reserved.  /out:test.dll /dll /implib:test.lib test.obj    creating library test.lib , object test.exp 

now use 32-bit python:

c:\>py -2 python 2.7.13 (v2.7.13:a06454b1afa1, dec 17 2016, 20:42:59) [msc v.1500 32 bit (intel)] on win32 type "help", "copyright", "credits" or "license" more information. >>> ctypes import * >>> lib = cdll('test') >>> lib.sum(2,3) 5 

if compile c++, can still call functions exporting them c, prevents c++ name mangling:

//test.cpp extern "c" __declspec(dllexport) int sum(int a, int b) {     return + b; }