How to Automate Exporting .NET Function to Unmanaged Programs

static Assembly CurrentDomain_AssemblyResolve(object sender, ResolveEventArgs args)
{
	try
	{
		return Assembly.LoadFrom(Path.Combine(Path.GetDirectoryName(filepath), args.Name.Split(',')[0] + ".dll"));
	}
	catch (Exception)
	{
		return null;
	}
}

AppDomain.CurrentDomain.AssemblyResolve += delegate(object sender, ResolveEventArgs resolveArgs)
{
    try
    {
        return Assembly.LoadFrom(Path.Combine(Path.GetDirectoryName(filepath), resolveArgs.Name.Split(',')[0] + ".dll"));
    }
    catch (Exception)
    {
        return null;
    }
};

char* fun()
{
  char a[8];
  a[0] = 'i';
  a[1] = ' ';
  a[2] = 'c';
  a[3] = 'a';
  a[4] = 'n';
  a[5] = ''';
  a[6] = 't';
  a[7] = '\0'; 
  return a;
}

        
[ExportDllAttribute.ExportDll("Summe")]
public static int Summe(int A, int B, [MarshalAs( UnmanagedType.AnsiBStr)] ref string os)
{
  os = A.ToString() + B.ToString() + " ok";
  return A + B;
}

Private Declare Function Summe Lib "MyLib.dll" (ByVal A As Long, ByVal B As Long, ByRef S As String) As Long

Sub test()
Dim S As String
i = Summe(10, 10, S)
MsgBox S
End Sub

namespace ZufallArray
{
    public class ZufallArray
    {
        [ExportDllAttribute.ExportDll("ZArray",
        System.Runtime.InteropServices.CallingConvention.Cdecl)]
        public static int ZArray(int beginn, int ende, int anzahl, [MarshalAs(UnmanagedType.LPArray,
        SizeParamIndex=1)] ref int[] ZZahl)
        {
            //int[] ZZahl = new int[anzahl]; 
            Random randObj = new Random();
            for (int j = 0; j < anzahl; j++)
            {
                ZZahl[j]= randObj.Next(beginn, ende);
            }
            //return ZZahl;
            return 1;
        }
    }
}

Declare Function Zar Lib _
"C:\.........\ZufallArray.dll" _
 Alias "ZArray" (ByVal a As Integer, ByVal b As Integer, ByVal c As Integer, ByRef d() As Integer) As Integer
 

Sub zarray()
Dim a() As Integer
Dim x As Integer
x = Zar(10, 20, 3, a())
For i = 0 to 2
    MsgBox a(i)
Next i
End Sub

namespace ZufallArray
{
    public class ZufallArray
    {
        [ExportDllAttribute.ExportDll("ZArray",
        System.Runtime.InteropServices.CallingConvention.Cdecl)]
        public static int[] ZArray(int beginn, int ende, int anzahl)
        {
            int[] ZZahl = new int[anzahl]; 
            Random randObj = new Random();
            for (int j = 0; j < anzahl; j++)
            {
                ZZahl[j]= randObj.Next(beginn, ende);
            }
            return ZZahl.MarshalAs ...... (something):~;
        }
    }
;

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;

namespace ZufallArray
{
    public class ZufallArray
    {
        [ExportDllAttribute.ExportDll("ZArray",
        System.Runtime.InteropServices.CallingConvention.Cdecl)]

        //Applied to a return value.
        [return:MarshalAs(UnmanagedType.LPArray, SizeParamIndex=1)]
        public static int[] ZArray(int beginn, int ende, int anzahl)
        {
            int[] ZZahl = new int[anzahl]; 
            Random randObj = new Random();
            for (int j = 0; j < anzahl; j++)
            {
                ZZahl[j]= randObj.Next(beginn, ende);
            }
            return ZZahl;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;


namespace classtest
{
    public class test
    {
        [ExportDllAttribute.ExportDll("Stringtest",
        System.Runtime.InteropServices.CallingConvention.Cdecl)]
        [return: MarshalAs(UnmanagedType.AnsiBStr)]
        public static string Stringtest()
        {
            String Meld = "Geht doch!";
            return Meld;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
//[return: MarshalAs(UnmanagedType.SafeArray, SafeArraySubType = VarEnum.VT_I4)] 
//[return: MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 1)] 
namespace classtest
{
    public class test
    {
        [ExportDllAttribute.ExportDll("ArrayTest",
        System.Runtime.InteropServices.CallingConvention.Cdecl)]
        [return: MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 1)] 
        public static int[] ArrayTest(int beginn, int ende, int anzahl)
        {
            int[] ZZahl = new int[anzahl];
            Random randObj = new Random();
            for (int j = 0; j < anzahl; j++)
            {
                ZZahl[j] = randObj.Next(beginn, ende);
            }
            return ZZahl;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace ALWSLib
{
    public class ALWSLibClass
    {
        [ExportDllAttribute.ExportDll("DLLMsgBox", CallingConvention.StdCall)]
        [return: MarshalAs(UnmanagedType.AnsiBStr)]
        public static string MsgBox([MarshalAs(UnmanagedType.AnsiBStr)] string message, [MarshalAs(UnmanagedType.AnsiBStr)]string caption, int buttons, int icon)
        {
            MessageBox.Show(message, caption, (MessageBoxButtons)buttons, (MessageBoxIcon)icon);
            return "I am the return message from the managed function!";
        }

        [ExportDllAttribute.ExportDll("AddAndReturnAsString", CallingConvention.Cdecl)]
        [return: MarshalAs(UnmanagedType.AnsiBStr)]
        public static string AddAndReturnAsString(int A, int B)
        {
            MessageBox.Show("In managed function :  AddAndReturnAsString(" + A + ", " + B + "). Returning sum ...");
            return (A + B).ToString();
        }

    }
}

unit Main;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Edit1: TEdit;
    Edit2: TEdit;
    CbxLoaded: TCheckBox;
    Button4: TButton;
    Edit3: TEdit;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

  ALWSLibInitialized: boolean;

implementation

{$R *.DFM}

type TDLLMsgBox = function(
  aMsg: PChar;
  aTitle: PChar;
  aButtons: Integer;
  aIcon: Integer): PChar; stdcall;

type TAddAndReturnAsString = function(
  A: integer;
  B: integer): PChar; cdecl;


// Global Handle for the Lib
var ALWSLibHandle: THandle;

// Global Handles for the DLL-functions
const PAddAndReturnAsString: TAddAndReturnAsString = nil;
const PDLLMsgBox: TDLLMsgBox = nil;

// ----------------------------------------------------------------------------

function DoLoadDLL(ADLL: String): THandle;
var
  FileOK: Boolean;
begin
  FileOK := FileExists(ADLL);
  if FileOK then
    Result := LoadLibrary(PChar(ADLL));
  if Not(FileOK) or (Result < hInstance_Error) then
    begin
    MessageDlg('DLL ('+ADLL+') not installed.', mtError,[mbOK],0);
    ALWSLibInitialized := False;
    Abort;
    end;
end;

procedure ALWSLibInitialize;
var
  ADLL: String;
begin
  if not(ALWSLibInitialized) then
    begin
    ALWSLibInitialized := True;
    ADLL := ExtractFileDir(Application.ExeName)+'\..\DLL\ALWSLib.dll';
    ALWSLibHandle := DoLoadDLL(ADLL);
    if not(ALWSLibHandle < hInstance_Error) then
      begin
      @PAddAndReturnAsString := GetProcAddress(ALWSLibHandle, 'AddAndReturnAsString');
      @PDLLMsgBox := GetProcAddress(ALWSLibHandle, 'DLLMsgBox');

      if not(Assigned(@PAddAndReturnAsString)) or
         not(Assigned(@PDLLMsgBox)) then
        begin
        MessageDlg('Incorrect Library module '+ADLL, mtError,[mbOK],0);
        Abort;
        end;
      end;
    end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  ALWSLibInitialize;
  CbxLoaded.Checked := (ALWSLibInitialized);
end;

procedure TForm1.Button2Click(Sender: TObject);
var
  A, B : integer;
  Res: PChar;
  StrRes: String;
begin
  A := 123;
  B := 456;
  // Add 123 en 456
  if ALWSLibInitialized then
    begin
    // call Lib
    Res := PAddAndReturnAsString(A, B);
    SetString(StrRes, Res, StrLen(Res));
    Edit1.Text := StrRes;
    end;
end;

procedure TForm1.Button3Click(Sender: TObject);
var
  aMessage, aCaption : String;
  A, B : integer;
  Res: PChar;
  StrRes: String;
begin
  aMessage := 'Het is hier goed weer in .Net land...';
  aCaption := 'MsgBox in .Net';
  A := 0;
  B := 32;
  // Send message and get some back ...
  if ALWSLibInitialized then
    begin
    // call Lib
    Res := PDLLMsgBox(PChar(aMessage),
                      PChar(aCaption),
                      A, B);
    SetString(StrRes, Res, StrLen(Res));
    Edit2.Text := StrRes;
    end;
end;

initialization
  ALWSLibInitialized := false;

end.