importance of dllexport location in program
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Hi,
(using MS VS2005) Recently I've found that in order for a function to be exported, dllexport *must* be placed in the same file of the function body. E.g. see the following case:
File a.cpp
File b.cpp
Now, a.cpp and b.cpp compile perfectly into a dll. However a() is not exported.
From what I understand from MSDN, dllexport is supposed to substitute the export section in the .DEF file - seems that it doesn't. Is this an MS bug?
Thanks,
Gil.
(using MS VS2005) Recently I've found that in order for a function to be exported, dllexport *must* be placed in the same file of the function body. E.g. see the following case:
File a.cpp
C++ Syntax (Toggle Plain Text)
File b.cpp
C++ Syntax (Toggle Plain Text)
Now, a.cpp and b.cpp compile perfectly into a dll. However a() is not exported.
From what I understand from MSDN, dllexport is supposed to substitute the export section in the .DEF file - seems that it doesn't. Is this an MS bug?
Thanks,
Gil.
Here is an explaination of how I use it. I always use it with __declspec and don't have a problem. It does not affect the .DEF file -- actually the DEF file is not even needed when dllexport is used.
Last edited by Ancient Dragon : May 9th, 2008 at 5:04 pm.
Oh, of course, forgot to mention the __declspec. Well, it is there.
Try out the scenario I depicted and see that although no link problems, a() is not being exported.
Gil.
Try out the scenario I depicted and see that although no link problems, a() is not being exported.
Gil.
Is b.cpp the application program that is calling the exported function in a.cpp, which is in a dll ?
In b.cpp you need to declare the function as _dllimport.
In b.cpp you need to declare the function as _dllimport.
// b.cpp is the application program
//
_delspec(_dllimport) void a();
void foo()
{
a();
} No, both a.cpp and b.cpp are files that compile into one dll. I did not specify the client to that dll.
Gil.
Gil.
>>From what I understand from MSDN, dllexport is supposed to substitute the export section in the .DEF file -
Your understanding is incorrect. What MSDN means is that you can export the function in one of two ways:
The compiler does not make any entries into the .DEF file for you -- you have to do that yourself if you want them there.
Prototyping the function as you did in a.cpp is not sufficient. You have to add dllexport in the function itself
You can also export an entire c++ class
Your understanding is incorrect. What MSDN means is that you can export the function in one of two ways:
- use the __dllspec( __dllexport ) tags
- add an entry into the .DEF file
The compiler does not make any entries into the .DEF file for you -- you have to do that yourself if you want them there.
Prototyping the function as you did in a.cpp is not sufficient. You have to add dllexport in the function itself
a.cpp
__dllspec( __dllexport ) void a()
{
// blabla
}You can also export an entire c++ class
__dllspec( __dllexport) class MyClass
{
// blabla
} Last edited by Ancient Dragon : May 10th, 2008 at 9:15 am.
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