C++ / C# - Creating a DLL With Visual C++ 2008 Express Edition

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Xenocythe

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Posted: 7th Mar 2008 01:44

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I searched the forums and google, and both have led me to nowhere.

I'm sure this must be possible...

Can anyone take me step by step to start me off with creating a DLL to work with DBPro using Visual C++ 2008 Express Edition?

Thanks.

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Dr Schnitzengruber

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Posted: 7th Mar 2008 04:33

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Okay, here it goes:

1) Create a new empty project (with nothing in it)

2) In the solution explorer, right click on the solution(should be second from top) and click properties.

3) In the top of the properties window click configuration manager.

4) Set the active solution configuration to release and close the configuration manager.

5) In the properties window, click "Configuration Properties->General"

6) Set "Project defaults->Configuration Type" to dynamic link library.

7) Close the properties window.

8) Add a source file(.cpp) somewhere in the solution.

9) Add this code to it:

+ Code Snippet

#define DLLEXPORT extern "C" __declspec(dllexport)

10) Create your dll functions. All functions accessible to dark basic must be marked with DLLEXPORT before the declaration.

11) To test your code, compile the solution and copy the output dll file to any darkbasic projects folder. You can use it with the call dll and load dll commands. When using the call dll command, the entry point name is the same as the name of the function in c++.

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Xenocythe

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Posted: 7th Mar 2008 04:43

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Thanks very much

A couple more questions;

Is it only accessable through load dll? Can I drop it in the plugins user folder, and let it work it's own magic?

The most confusing part is yet to be making the dll functions. Can you give a small example, such as an Add() function, that adds two numbers together?

Thank you very much so far. You've cleared quite a lot up.

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Dr Schnitzengruber

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Posted: 7th Mar 2008 04:52

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Quote: "Is it only accessable through load dll?"

No, you have to add a resource file to make it a plug-in. But I never do that so I have no clue how.

Quote: "The most confusing part is yet to be making the dll functions. Can you give a small example, such as an Add() function, that adds two numbers together?"

+ Code Snippet

DLLEXPORT int Add(int A,int B)
{
 return A + B;
}

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Xenocythe

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Posted: 7th Mar 2008 05:00

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Oh, I see, that bit of code was quite simple.

Well, I've figured out that Visual C++ 2008 Express Edition does not allow resource editing with the free version. You can, however, add a text file, and save it as .rc for a string table I presume.

Does anyone know how I can use that text file .rc trick to make a string table? What should the string table file look like, say, for that add function?

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Benjamin

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Posted: 7th Mar 2008 12:14

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Quote: "Well, I've figured out that Visual C++ 2008 Express Edition does not allow resource editing with the free version."

Right-click the file in the editor and select view source.

Quote: "Does anyone know how I can use that text file .rc trick to make a string table?"

Add a file (of any type) to the project, and rename the extension in the IDE.

Quote: "What should the string table file look like, say, for that add function?"

Assuming you use extern "C" to export the function with an undecorated name:

+ Code Snippet

STRINGTABLE
BEGIN
	1, "ADD[%LLL%Add"
END

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jinzai

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Posted: 7th Mar 2008 14:59 Edited at: 7th Mar 2008 23:07

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It is an accepted best practice to start string resource values at 101. Lower IDs are already taken by Windows. That is not usually a problem, but it can be if you start using Windows components. It is always a good idea to play well with Windows.

Having said that, here is my bit on how to create a DLL with VC++ 2008:

1. On the menu bar, select File/New/Project.
2. Select Win32 Project.
3. Type the name you want to give the DLL in the Name field.
4. Select Application Settings on the Win32 Application Wizard dialog.
5. Set Application type to DLL, and select Export Symbols.

You must create two files for the resources. (The string table used to export your functions to DBPro is a resource.)

resource.h
projectname.rc

Both files are text. To do this:

1. Select File/New/Visual c++/Header File
2. Type this into the file:
	#define IDS_STRING101	101
3. Save this to the project directory as resource.h

4. Select File/New/General/Text File
5. Type this into the file:
        #include "resource.h"
        STRINGTABLE
	BEGIN
		IDS_STRING101	"put the string for your command here."
	END
6. Save this in the project directory as projectname.rc
7. In the Solution Explorer pane, right click on Header Files. Select Add/Existing Item.
8. Select resource.h
9. In that same pane, right click Resource Files. Select Add/Existing item.
10. Select projectname.rc

Add new commands by adding the resource ID definition to resource.h, and the string to projectname.rc

+ Code Snippet

1. On the menu bar, select File/New/Project.
2. Select Win32 Project.
3. Type the name you want to give the DLL in the Name field.
4. Select Application Settings on the Win32 Application Wizard dialog.
5. Set Application type to DLL, and select Export Symbols.

You must create two files for the resources. (The string table used to export your functions to DBPro is a resource.)

resource.h
projectname.rc

Both files are text. To do this:

1. Select File/New/Visual c++/Header File
2. Type this into the file:
	#define IDS_STRING101	101
3. Save this to the project directory as resource.h

4. Select File/New/General/Text File
5. Type this into the file:
        #include "resource.h"
        STRINGTABLE
	BEGIN
		IDS_STRING101	"put the string for your command here."
	END
6. Save this in the project directory as projectname.rc
7. In the Solution Explorer pane, right click on Header Files. Select Add/Existing Item.
8. Select resource.h
9. In that same pane, right click Resource Files. Select Add/Existing item.
10. Select projectname.rc

Add new commands by adding the resource ID definition to resource.h, and the string to projectname.rc

Replace projectname with the name of the project.
Hope that helps.

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Sven B

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Posted: 7th Mar 2008 16:47

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I'm using decorated names with VC++ 2008 express.
You can find them by opening the DLL with notepad and then search them (CTRL + F) by function name. They're always preceeded by ? and split by (a) space(s).

It's the programmer's life:
Have a problem, solve the problem, and have a new problem to solve.

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Xenocythe

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Posted: 7th Mar 2008 21:37

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Alright, I'm getting somewhere

Thanks Benjamin for the string table info, Shnitz for starting me off, and jinzai for the awesome tutorial as well.

I only have one problem. Following jinzai's advice, I added resource.h to the project with this code:

+ Code Snippet

#define IDS_STRING101	101

When I build, I get an error in my string table code:

+ Code Snippet

        STRINGTABLE
	BEGIN
		IDS_STRING101	"ADD[%LLL%Add"
	END

It highlights IDS_STRING101 and says that it's undefined. I'm sure that resource.h and the string table are saved and added to the project. What's the dealio?

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Benjamin

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Posted: 7th Mar 2008 23:00

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You need to #include resource.h at the top of the resource file.

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jinzai

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Posted: 7th Mar 2008 23:07

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oops, thanks Benjamin!

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Xenocythe

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Posted: 7th Mar 2008 23:31

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I knew it was something simple like that. I just assumed everything was auto included into everything.

------AFTER TESTING-------
Well, I included that file, then I ran into a whole bunch of errors with the 'define' code, blah blah... so I put the resource.h 'define' code at the top of the string rable .rc file, replacing the 'include'. All I need is the string table .rc code, which now looks like this:

+ Code Snippet

#define IDS_STRING101	101
STRINGTABLE
	BEGIN
		IDS_STRING101	"ADD[%LLL%Add"
	END

I built the plugin, successfully, put it in plugins-user, and wa-la! I my add command worked great

Thanks big time everyone. I really appreciate all the help.

Thanks,
Xeno

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jinzai

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Posted: 7th Mar 2008 23:38 Edited at: 7th Mar 2008 23:39

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You're welcome. FYI, that is also Luke Escude's trouble...it is caused by cut and paste. When you do that, there is no carriage return at the end of the line, and the compiler gets confused. If you put the cursor at the end of the line and press enter, it will not have those errors.

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Xenocythe

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Posted: 7th Mar 2008 23:51

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Oh snap

I'll just do that.

Say, if I have two commands... does it look like this?

+ Code Snippet

#define IDS_STRING101	101
#define IDS_STRING102	102

Also, if L is integer in a string table, S would be string, right?

Thank you.

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jinzai

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Posted: 8th Mar 2008 00:07

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Yes, it does. Certainly, you are free to name the ID anything reasonable. By convention, strings are "IDS_" something...menus are "IDM_" something, controls are "IDC_" something, etc.

Yes on #2 as well.

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