Consume an external DLL functions in a visual studio 2017 program

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Good Evening to everybody.

I recently gave up in trying to consume an external dll functions in an old Access 2010 app, it just never worked; so I'm trying to use a new Project (program) that I'm developing as a desktop application with VS 2017 and VB NET, to use it as a proxy to consume the functions of this dll and returns the results to the Access 2010 app.

The program in VS 2017 indeed recognizes the dll, its attributes and functions.

I already got to connect the two apps, sending back and forth the necessary parameters through the clipboard, and even assignig values to several of its attributes. But when I try to execute a public function, the program fails, and the debug output window (I hpe is correct to say so) gives me the message (spanish):

'Facturacion_Electronica.exe' (CLR v4.0.30319: Facturacion_Electronica.exe): 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\FacturacionElectronica\v4.0_1.0.0.0__d18e1c28d757c7cd\FacturacionElectronica.dll' cargado. No se encuentra el archivo PDB o no se puede abrir.
Excepción producida: 'System.IO.FileNotFoundException' en Facturacion_Electronica.exe
El programa '[4416] Facturacion_Electronica.exe' terminó con código 0 (0x0).

It means something like. "Facturacion_Electronica.dll loaded. The PDB file couldn't be found or it cannot be opened".

If I use the statement "on error resume next" (just to avoid the program from stopping, and analyze the next functions, the error is (more or less):

"public function Boolean Grabar_Factura is missing or it can´t be found2

I saw this function comes in another dll that probably is referenced in (or called from) the first one I indeed can see the function with the object browser. It does exists, so I just don't know and can't figure out why it is not found in the program.

I'd really appreciate anybody's help or indications or hints about where to look for information to solve this problem. If I can't achieve this, the only option that I have left is to develop this functionality by myself, and it it would take me a long time. It's all about an electronic invoice generation.

What I have tried:

I've been trying to solve it, searching thru the internet for a great time. I'm aware I need to keep on searching, but I'd really like to save time.

Posted 18-Jan-18 12:12pm

Miguel Altamirano Morales

Updated 20-Jan-18 13:14pm

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phil.o 18-Jan-18 20:17pm

A few questions :)
- This external dll, which type is it? A .NET dll, or a c/c++ one?
- Can you show the exact error message you get?
Please, use the "Improve question" green widget to add details.

Miguel Altamirano Morales 19-Jan-18 10:46am

Thank you very much for your reply, Phil. I updated my question as you suggested me.

The second error message appears only if I set the "on error resume next" statement in my procedure and is not exactly how I wrote it, but the idea is the same. If I don't use the "on error...." statement the program stops with the first error.

I'm thinking that maybe solving the first error, the subsequent could be arranged automatically.

Miguel Altamirano Morales 19-Jan-18 11:23am

the dll is a NET one

Dotnet_Dotnet 19-Jan-18 10:55am

sir the dll is managed coded or unmanaged

Miguel Altamirano Morales 19-Jan-18 11:26am

Dotnet: Thanks for replying. Excuse me, I don't know that. I did not developed it. It was given by an ex-employee,and we don´t have the source code.

Is there a way to check that ?

Miguel Altamirano Morales 19-Jan-18 13:18pm

It must be a managed one, as far as I have read.

Dotnet_Dotnet 20-Jan-18 2:29am

copy the dll and pest it in your bin directory then take the reference of the dll to your project by right click on the project explorer

Dotnet_Dotnet 20-Jan-18 2:31am

if c# code then use the dll by calling at the top of the page like
using System.Linq;
you can write

using dllname;

Miguel Altamirano Morales 20-Jan-18 14:53pm

Thank you very much Dotnet.

Yes, I alredy have done that, and my program (a VB 2017 Project) indeed recognizes the dll; in fact I can assign values to several of its attributes, but when I try to execute an internal public function the program fails, telling me the function cannot be found.
It's weird because I can see the function in the Object Browser and in the definition of the dll (or due to a lot of ignorance on my part); I even added references to other dlls I think could be related in between each other.
When the program aborts, the output debug window tells that a .PDB file could not be found, so I also copied all the corresponding PDB's to the dlls I'm trying to use in the bin\debug folder.
In the meantime, I'm starting to develop a new Project trying to emulate the funcionality I was expected in the dll. And also I'm going to study p/invoke as another friend in this portal suggested me.

Thanks a lot, and if you think have another suggestion, please let me know.

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Southmountain · Answer 1 · 2018-01-20T11:53:00

Solution 1

Give a try:You can disassemble it,find the class and methods definitions, build your .def file,then use it as other regular DLL.

Posted 20-Jan-18 11:53am

Southmountain

Southmountain · Answer 2 · 2018-01-20T13:14:00

Solution 2

take a look at this post:

Create .lib file from .dll

Posted 20-Jan-18 13:14pm

Southmountain

Comments

Miguel Altamirano Morales 20-Jan-18 19:23pm

Thank you very much my friend Southmountain (such a nice name).

The post you sent me in your second solution is for achieve the first one ?.

I'll read carefully what you suggested me.