Question

In this code:

void Window::oops()  { printf("Window oops\n"); } 
void TextWindow::oops() { 
printf("TextWindow oops %d\n", cursorLocation);
}
TextWindow x; 
Window      a; 
Window     *b; 
TextWindow *c; 
a = x; a.oops();   // executes Window version 
b = &x; b->oops(); // executes TextWindow or Window version 
c = &x; c->oops(); // executes TextWindow version

What does it mean that b = &x; b->oops(); will execute the TextWindow or Window version? How is it decided?

Answer 1

If oops() is virtual, the b->oops() call will use the TextWindow version. If it is not, it will use the Window version.