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Really? I didn't know that. Shows how much I have still to learn about C. A program I'm writing now uses void* as a generic function pointer, which I cast to d

• kragen 16y ago
  I believe there is not a standard way to do what you are doing. However, in common implementations of C, you'll only have trouble if some of your functions have a different calling convention than others — stdcall, say, or fastcall, or Pascal calling convention, or far vs. near calls on 16-bit x86. I assume you can avoid that with a union with one member for each calling convention, but I've never tried it. Architectures where code pointers are bigger than data pointers are fairly exotic, I think. The AS/400 might be an example, I'm not sure. However! You can avoid that particular problem by using (void* )(void) as your generic function pointer type, rather than simply void *.
• JoachimSchipper 16y ago
  Pretty much the only standard way to do this involves something like "void (fp)(void arg)" or "void (*fp)(va_list ap)" and generous casting. That said, this is not that likely to be a problem in practice on Unix machines (Windows has more than one calling convention - I have no idea how much of a problem that is.)
• caf 16y ago
  It's guaranteed that function pointers survive a round-trip conversion to other function pointer types - so you can just use a type like `void (*fp)()` as a "generic" container, making sure that it's cast back to the correct type before use.