[2 days left] What’s wrong with your cloud strategy? Learn why multicloud solutions matter with Nimble Storage.Register Now

x
?
Solved

Cant find DLL reference point

Posted on 2000-02-23
3
Medium Priority
?
166 Views
Last Modified: 2012-05-04
I used C++ V6 to compile and link a DLL that includes function calls.  When I try to access functions from this DLL, I get the run-time error "Can't find DLL entry point ClfyConnect in notes2clarifydll".

I am thinking the problem is with the C++ DLL.

//////////////////////////
Sample calling code (VB6)...
Private Declare Function ClfyConnect Lib "notes2clarifydll" _
    (ByVal sServer As String, ByVal sDatabase As String, _
     ByVal sUsername As String, ByVal sPassword As String) As Long

////////////////////////////////
Sample C++ code generating the DLL...

__declspec(dllexport) long __stdcall ClfyConnect(char *,char *,char *,char *);
0
Comment
Question by:GregoryGr
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
3 Comments
 
LVL 22

Accepted Solution

by:
nietod earned 400 total points
ID: 2551666
The problem is name decoration.  I have a "stock answer" I'll post it.
0
 
LVL 22

Expert Comment

by:nietod
ID: 2551678
C++ "decorates" or "mangles" function names by appending a "code" to the end of the name that expresses the parameters passed to the function.  This is used to impliment function overloading, where 2 or more distinct functions have the same name and different parameters.  (Apparently they have the same name--C++ mangles the names so they don't actually have the same name).  

The function is exported with the mangeled name, so you aren't actually specifying the right name in VB.  You can use dumpbin to verify this, you should see the function exported with a mangeled name and that is the name that you woudl have to specify to VB

To fix this problem, you can specify the mangeled name to VB, or--better--declared the function as "extern "C" ".  This dissables name mangeling on the function.

Let me know if you have questions.
0
 
LVL 22

Expert Comment

by:nietod
ID: 2551695
One more thing.  This may not be quite sufficient.  There is one other type of name decoration and this doesn't dissable that.  If after using extern "C" you find that the exported name (check with dumpbin) ends with a "@" followed by a number, they this is the standard call decoration.  

To remove this decoration you need to place an entry in the DLL's module defintion file (.def).  The entry should appear in the EXPORTS section and should just contain the name of the function.  for example

// in your .cpp file

extern "C" __declspec(dllexport) long __stdcall ClfyConnect(char *,char *,char *,char *);

// in your .def file.
EXPORTS
   ClfyConnect

let me know if you have any questions
0

Featured Post

Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

IntroductionThis article is the second in a three part article series on the Visual Studio 2008 Debugger.  It provides tips in setting and using breakpoints. If not familiar with this debugger, you can find a basic introduction in the EE article loc…
Many modern programming languages support the concept of a property -- a class member that combines characteristics of both a data member and a method.  These are sometimes called "smart fields" because you can add logic that is applied automaticall…
The goal of the tutorial is to teach the user how to use functions in C++. The video will cover how to define functions, how to call functions and how to create functions prototypes. Microsoft Visual C++ 2010 Express will be used as a text editor an…
The goal of the video will be to teach the user the concept of local variables and scope. An example of a locally defined variable will be given as well as an explanation of what scope is in C++. The local variable and concept of scope will be relat…
Suggested Courses

649 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question