c - Strange pointer casting with void * -

c - Strange pointer casting with void * -

we working on project embedded linux c , c++ together. recenty encountered unusual statement in function:

bool strangefunction(void* arg1, void* arg2, void* arg3) { (void)arg1; (void)arg2; (void)arg3; unsigned long keycode = (unsigned long)arg2; switch(keycode) { ...

i have 2 question in code above

what mean (void)arg1; ? is possible , ok utilize unsigned long keycode = (unsigned long)arg2;

if don't mind, need explanation , related links explaining subjects. thanks.

it quiet compiler warnings unused parameters.

it possible not portable. if on given platform address fits unsigned long, it's fine. utilize uintptr_t on platforms available create code portable.

c casting void-pointers