DLL loading syntax Is there some hidden problem?

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I use this syntax for defining type of functions loaded from DLL

C#

typedef void* (*unknown)(
#ifdef __cplusplus
...
#endif
);

And then retype loads
unknown varname= (unknown)GetProcAddress(hGetProcIDDLL, "FuncName");

This gives me ability to use any function (int,int,int) (char*,int,char*) for example with no problems.

And I want to know if there is some special situation in which this can't be used or it will not work the way I explained higher?

Posted 12-Mar-13 8:49am

Timotej Tomandl

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2 solutions

Solution 1

It should work in all cases. Why not?

However, your sample looks strange due to the weird name "hGetProcIDDLL", because first parameter is the DLL module ID obtained, obtained using LoadLibrary, LoadLibraryEx, LoadPackagedLibrary, or GetModuleHandle:
http://msdn.microsoft.com/en-us/library/windows/desktop/ms683212%28v=vs.85%29.aspx[^].

So, your first step should be obtaining the module handler, so you could use it as a first parameter. See the respective MSDN help pages, starting from the page referenced above.

—SA

Posted 12-Mar-13 9:21am

Sergey Alexandrovich Kryukov

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Espen Harlinn 12-Mar-13 17:56pm

5'ed!

Sergey Alexandrovich Kryukov 12-Mar-13 18:00pm

Thank you, Espen.
—SA

Timotej Tomandl 13-Mar-13 15:32pm

It is the name of class hinstances from tutorials.

Sergey Alexandrovich Kryukov 13-Mar-13 15:35pm

Formally, it does not matter, but I'll advise you to use better names; the one from Windows API documentation is better.
Are you clear with your doubt? Will you accept the answer formally now (green button)?
—SA

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nv3 · Accepted Answer · 2013-03-12T09:49:00

Although I have never tried it, I'd say that there is a good chance that the little trick with "..." will work.

But you are depriving yourself from all the type checking that the compiler can do for you. Let's say, the function you are calling has a signature of (int, int) and instead you call it with (char*, double, double). That might result in totally unpredictable behavior of the program. The function might not even return properly. And such errors are sometimes very hard to debug.

So, I'd recommend: Do yourself a favor and define the types of the functions in your DLL properly and give the compiler a chance to detect errors in the argument sequence.