FileNotFoundError: Could not find module 'E:\...\exp_simplifier\ExpSim.dll' (or one of its dependencies)

Question

Hope you're having a great day!

I have created an ExpSim.dll file that I compiled from Visual Studio 2022 in a DLL project. Here is the main code:

#include "ExpressionSimplifier.h"
#include <Windows.h>
#include <Python.h>

exs::ExprSimplifier simplifier = exs::ExprSimplifier();

extern "C" __declspec(dllexport)
PyObject* _cdecl getSteps()
{
    // some code
}

extern "C" __declspec(dllexport)
void _cdecl getSimplifiedExpressionSize(const char* expression)
{
    // some code
}

extern "C" __declspec(dllexport)
const char* _cdecl getSimplifiedExpression(const char* expression)
{
    // some code
}


BOOL APIENTRY DllMain( HMODULE hModule,
                       DWORD  ul_reason_for_call,
                       LPVOID lpReserved
                     )
{
    switch (ul_reason_for_call)
    {
    case DLL_PROCESS_ATTACH:
    case DLL_THREAD_ATTACH:
    case DLL_THREAD_DETACH:
    case DLL_PROCESS_DETACH:
        break;
    }
    return TRUE;
}

Now in python, when I run the following code:

from ctypes import *

exp_sim = cdll.LoadLibrary("python/maths/exp_simplifier/ExpSim.dll")
exp_sim.getSteps.restype = c_char_p

exp_sim.simplifyExpression.argtypes = [c_char_p]
exp_sim.simplifyExpression.restype = py_object

result = exp_sim.simplifyExpression(b"x+y+x")

print(result)

It shows the following error at line 3:

Traceback (most recent call last):
  File "e:\Python Stuff\Projects\Minisoft\python\maths\exp_simplifier\exp_simplifier.py", line 3, in <module>
    exp_sim = cdll.LoadLibrary("python/maths/exp_simplifier/ExpSim.dll")
  File "C:\Users\Saket\AppData\Local\Programs\Python\Python310\lib\ctypes\__init__.py", line 452, in LoadLibrary
    return self._dlltype(name)
  File "C:\Users\Saket\AppData\Local\Programs\Python\Python310\lib\ctypes\__init__.py", line 374, in __init__
    self._handle = _dlopen(self._name, mode)
FileNotFoundError: Could not find module 'E:\Python Stuff\Projects\Minisoft\python\maths\exp_simplifier\ExpSim.dll' (or one of its dependencies). Try using the full path with constructor syntax.

Before I started using the Python API in my C++ code, the DLL seemed to work fine, but not after that. Firstly, it refused to compile my code due to it not being able to find python311_d.lib , and after fixing that, python refuses to read my DLL.

I believe it's due to ExpSim.dll still having a dependency on python311_d.lib , but I have no idea how to fix that in VS Code.

Any help would be appreciated. Have a good day!

Answer 1

My suggestion is to replace the following code with line 2 of your python code:

exp_sim = cdll.LoadLibrary("./python/maths/exp_simplifier/ExpSim.dll")

You can also see some explanations here .