Re: extern "C" and C++ conventions when passing parameters

"Earl Purple" <>
5 Oct 2006 23:38:32 -0400
Naven wrote:

Hi all,

i have a doubt whether the following is standard C++ or it "just"
compiles for whatever reason:

I created a DLL with an exported function

extern "C" void myFunction(std::vector<AbstractClass*> theVector)

DLLs are not part of standard C++, which doesn't recognise the concept
of libraries.

The extern "C" i need for correctly
unmangling the name because i call the function with fnPtr =

Then I call this function from the main program, passing a vector
filled with objects of type MyDerivedClass1* and MyDerivedClass2*.

At my big suprise, this code compiles and executes, virtual functions
of MyDerivedClassX are
correctly recognized, i.e. all works like standard C++.

No problem passing the abstract base class, that is perfectly portable.
What isn't perfectly portable is passing vector across. vector could be
differently implemented on different sides. Would be more portable to
pass a combination of AbstractClass** and a size. You can pass the
address of the first item of the vector because the contents are
guaranteed to be contiguous.

somebody tell me if this
is standard C++ and allowed and why?

Well I have already answered that. There is no C++ standard for DLLs or
shared libraries or any other kind of library use. STL collections and
std::string are not guaranteed to be portable across library boundaries.

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