C++ passing a function pointer twice causing issues

Question

I have a function pointer that I am trying to pass along to a class method, where pthread_create will be invoked to pass along that parameter. But I am getting some errors and not sure where I am suppose to go from here.

void (*FuncPointer)(void*);
FuncPointer = random_function;
ThreadPool.Task(FuncPointer);

int IOThreadPool::Task(void* (*FuncPointer)(void*))
{
    pthread_t NewThread;

    int rc = pthread_create(&NewThread, NULL, FuncPointer, (void *) (intptr_t) IOThreadPool::Threads.size() + 1);

main.cpp:57:29: error: invalid conversion from ‘void* (*)()’ to ‘void (*)(void*)’ [-fpermissive]

Please explain why even though I am passing it as void* (*)(void*), I get void* (*)(). I am very confused and my head has begun to hurt!

Thanks

could you provide random_function too? It has the correct signature? — Dutow
– Dutow, Commented Jul 22, 2016 at 14:33

eerorika · Accepted Answer · 2016-07-22 14:50:06Z

1

invalid conversion from ‘void* (*)()’ to ‘void (*)(void*)’

You forgot to show us the declaration of random_function, but judging from the error message, it appears to be

void* ranfom_function()

Since the signature of the function does not match the signature of FuncPointer (ranfom_function lacks the argument , and return type is different), you get the error.

Another bug, that is not shown by the error: The return type of FuncPointer does not match the return type of the argument accepted by IOThreadPool::Task (void vs void*).

Solution: Declare instad

void* ranfom_function(void*)

and

void* (*FuncPointer)(void*)

edited Jul 22, 2016 at 14:50

answered Jul 22, 2016 at 14:43

eerorika

240k13 gold badges212 silver badges354 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

user0000001 Over a year ago

You're the man. This was it. Thank you for explaining that to me... You also just shed a new light on this concept for me. I understand now why it wasn't working. Cheers to you!

Collectives™ on Stack Overflow

C++ passing a function pointer twice causing issues

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related