function pointer

A real example of function pointer is set_new_handler. It accepts a function pointer and return the same function pointer, so declaring such format is a little difficult.
void failNew(){
cerr<<"Fail␣now"<<endl
abort();
}
-----------------------------------------
extern void ( *set_new_handler ( void (*)() ) ) ();
// This function declaration is very complex.
set_new_handler(failNew);
A better method is to use typedef method.
typedef void(* FunPtr)();

FunPtr (*set_new_handler) (FunPtr);

set_new_handler(failNew);
in C++ 11, When you want to function pointer, encourage you to use more lambda idiom. You also can use auto to store a lambda function for future use.