Callbacks

void Foo();
void Bar();

int main()
{
  // define pointer to function, initialize to address of Foo
  void (*pF)() = &Foo;
  Foo();              // call Foo directly
  Bar();              // call Bar directly
  (*pF)();            // call Foo via pF  callback
  void (*pF2)() = pF; // make copy of pF
  pF = &Bar;          // change pF
  (*pF)();            // call Bar via pF  callback
  (*pF2)();           // call Foo via pF2 callback
}