unresolved overloaded function type

error: no matching function for call to class1::input(void*, unresolved overloaded function type)
note: candidates are: int class1::input(void*, int (class1::*)(void*, int))

if your function call is like
input( (void*)&cur_msg, class1::input);

change it to
input( (void*)&cur_msg, &class1::input);

Its basically a function pointer, so you need to pass address of that function