有下列程序: #include<iostream> using namespace std; class TestClass1 { public: TestClass1(){cout<<"A";} }; class TestClass2<public:TestClass2(){cout<<"B";} }; class TestClass3:public TestClass1{ TestClass2 b; public:TestClass3(){cout<<"C";} }; int main()(TestClass3 obj;return 0;} 执行该程序后的输出结果是______。