When I load the DLL path of a C# Class Library DLL, it either doesn't find it or the functions are not recognized or loaded. Even though it's the same runtime (i.e., .NET 9.0), I only get the status code as an error. Can someone explain why this is not working? I would be very grateful.

C++ Code:

#include <windows.h>
#include <iostream>
#include <string>
#include "hostfxr.h"
#include "coreclr_delegates.h"

typedef int (*component_entry_point_fn)(void* arg, int32_t arg_size_in_bytes);

void* load_library(const char_t* path)
{
    return LoadLibraryW(path);
}

void* get_export(void* lib, const char* name)
{
    return GetProcAddress((HINSTANCE)lib, name);
}

bool load_hostfxr(const std::wstring& runtime_config_path, hostfxr_initialize_for_runtime_config_fn& init_fn, hostfxr_get_runtime_delegate_fn& get_delegate_fn, hostfxr_close_fn& close_fn)
{
    std::wstring hostfxr_path = L"C:\\Program Files\\dotnet\\host\\fxr\\9.0.1\\hostfxr.dll";
    void* lib = load_library(hostfxr_path.c_str());
    if (!lib) return false;

    init_fn = (hostfxr_initialize_for_runtime_config_fn)get_export(lib, "hostfxr_initialize_for_runtime_config");
    get_delegate_fn = (hostfxr_get_runtime_delegate_fn)get_export(lib, "hostfxr_get_runtime_delegate");
    close_fn = (hostfxr_close_fn)get_export(lib, "hostfxr_close");

    return init_fn && get_delegate_fn && close_fn;
}

bool create_host_context(const std::wstring& runtime_config_path, hostfxr_initialize_for_runtime_config_fn init_fn, hostfxr_handle& ctx)
{
    hostfxr_initialize_parameters params{ sizeof(hostfxr_initialize_parameters), nullptr, nullptr };
    return init_fn(runtime_config_path.c_str(), &params, &ctx) == 0;
}

bool get_function_pointer(hostfxr_handle ctx, hostfxr_get_runtime_delegate_fn get_delegate_fn, load_assembly_and_get_function_pointer_fn& func_ptr)
{
    return get_delegate_fn(ctx, hdt_load_assembly_and_get_function_pointer, (void**)&func_ptr) == 0;
}

int main()
{
    std::wstring runtime_config = L"C:\\Users\\Reversed Codes\\Desktop\\testnative_cs\\bin\\Release\\net9.0\\win-x64\\publish\\testnative_cs.runtimeconfig.json";
    std::wstring dll_path = L"C:\\Users\\Reversed Codes\\Desktop\\testnative_cs\\bin\\Release\\net9.0\\win-x64\\publish\\testnative_cs.dll";
    hostfxr_initialize_for_runtime_config_fn init_fn;
    hostfxr_get_runtime_delegate_fn get_delegate_fn;
    hostfxr_close_fn close_fn;

    if (!load_hostfxr(runtime_config, init_fn, get_delegate_fn, close_fn))
    {
        std::wcerr << L"Fehler: hostfxr konnte nicht geladen werden." << std::endl;
        return -1;
    }

    hostfxr_handle ctx;
    if (!create_host_context(runtime_config, init_fn, ctx))
    {
        std::wcerr << L"Fehler: hostfxr-Initialisierung fehlgeschlagen." << std::endl;
        return -1;
    }

    load_assembly_and_get_function_pointer_fn load_assembly_fn;
    if (!get_function_pointer(ctx, get_delegate_fn, load_assembly_fn))
    {
        std::wcerr << L"Fehler: Konnte Delegate-Funktion nicht abrufen." << std::endl;
        return -1;
    }

    void* method_ptr;
    int result = load_assembly_fn(
        dll_path.c_str(),
        L"ManagedLibrary.HelloWorld",
        L"SayHello",
        UNMANAGEDCALLERSONLY_METHOD,
        nullptr,
        &method_ptr);

    std::cout << "Result: " << result << std::endl;


    if (result != 0)
    {
        std::wcerr << L"Fehler: Methode konnte nicht geladen werden." << std::endl;
        return -1;
    }

    auto managed_entry = (component_entry_point_fn)method_ptr;
    managed_entry(nullptr, 0);

    close_fn(ctx);
    return 0;
}

C# Code:

using System;
using System.Runtime.InteropServices;

namespace testnative_cs
{
    public class HelloWorld
    {
        [UnmanagedCallersOnly]
        public static int SayHello(IntPtr arg, int arg_size)
        {
            Console.WriteLine("Hallo aus C#!");
            return 0;
        }
    }
}

C# .csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net9.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <GenerateRuntimeConfigurationFiles>true</GenerateRuntimeConfigurationFiles>
    <Nullable>enable</Nullable>
  </PropertyGroup>

</Project>

output:

Result: -2146233054
Fehler: Methode konnte nicht geladen werden.

C:\Users\Reversed Codes\source\repos\TestNative\x64\Debug\TestNative.exe (Prozess "34156") wurde mit Code "-1" (0xffffffff) beendet.
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I am developing server software in C++ and want to add C# plugin support, but I am stuck on this function. I hope someone can fix it or provide a tip.