load native libraries in .NetCore 2.1 (Windows) - dll

Question

I am trying to load native libraries in .NetCore 2.1 like this:
[DllImport("kernel32.dll")]
public static extern IntPtr LoadLibrary(string dllToLoad);
[DllImport("kernel32.dll")]
public static extern bool SetDllDirectoryA(string lpPathName);
...
SetDllDirectoryA(pathToDll);
var pDll = LoadLibrary(pathToDll+dllName);
if (pDll == IntPtr.Zero)
{
throw new System.ArgumentException("DLL not found", "pDll");
}
But the function LoadLibrary returns zero always. This code works fine with .NET Framework.
I am not really sure if loading native libraries is supported in .NetCore. If it is possible what is the correct way to do it?

Answer 1

I think you are using a 32 bit DLL. In netcore, a 32bit DLL could not be loaded with a 64bit process.
Try this code to check:
class Program
{
[DllImport("kernel32.dll")]
public static extern IntPtr LoadLibrary(string dllToLoad);
static void Main(string[] args)
{
if (System.Environment.Is64BitProcess)
{
Console.WriteLine("This is 64 bit process");
}
var pDll = LoadLibrary("aDLL.dll");
if (pDll == IntPtr.Zero)
{
Console.WriteLine("pDll: " + pDll);
throw new System.ArgumentException("DLL not found", "pDll");
}
Console.WriteLine("pDll: " + pDll);
}
}
Update: If you want to force NetCore runs at x86 flatform (to use 32bit DLL). First download NetCore x86 from https://dotnet.microsoft.com/download/thank-you/dotnet-sdk-2.1.500-windows-x86-installer. Then you should edit .CSPROJ file by adding RunCommand and changing PlatformTarget to x86 :
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFramework>netcoreapp2.1</TargetFramework>
</PropertyGroup>
<PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">
<Prefer32Bit>false</Prefer32Bit>
<PlatformTarget>x86</PlatformTarget>
<Optimize>false</Optimize>
<RunCommand Condition="'$(PlatformTarget)' == 'x86'">$(MSBuildProgramFiles32)\dotnet\dotnet</RunCommand>
<RunCommand Condition="'$(PlatformTarget)' == 'x64'">$(ProgramW6432)\dotnet\dotnet</RunCommand>
</PropertyGroup>
</Project>