下列程序的输出结果是______。 #include <iostream> using namespace std; class A int a; public: A():a(9) virtual void print() constcout<<a;; ; class B: public A char b; public: B()b=’S’; void printo const cout<<b; ; void show(A&x) x.print(); int main() A d1,*p; B d2; d1.print(); d2.print(); p->print(); show(d1); show(d2); return 0;