错误：从'void（FlashWork :: *）（int，siginfo_t *，void *）'转换为'void *（*）（int，siginfo_t *，void *）'

Question

I am a C programmer (on linux), but now I have a project on C++, and have a question.

Here is sample code

g_action.sa_sigaction = (void(*)(int,siginfo_t*,void*))&FlashWork::Disconnect_action; 

When I try to compile this on x86, it works fine, but on arm I get the following error

error: converting from void (FlashWork::*)(int, siginfo_t*, void*) to void (*)(int, siginfo_t*, void*)

What am I doing wrong?

Answer 1

"Pointer to members" are not compatible with "pointers to functions", unless it's a static member. The reason is that a pointer to member needs an object (a FlashWork object) in your case.

Answer 2

Your function is a member function that returns a void . It should be a non-member function (or a static member function) that returns a void * .

Answer 3

Besides the fact the return value of the functions are different, you should know that in C++, when you have a member function ( which is not static ):

void (FlashWork::*)(int, siginfo_t*, void*)

The real signature (the one a C programmer likes to see) is this:

void (*)(FlashWork *, int, siginfo_t *, void *)

That FlashWork * parameter is a hidden pointer which can be referred to by this .

Therefore,

void (FlashWork::*)(int, siginfo_t*, void*)

and

void (*)(int, siginfo_t*, void*)

have different number of arguments.