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如下程序运行时的输出结果是。#includeusing namespace std;class Base{public:Base(){ }virtual void f(){cout<<"A";}};class D1: public Base {public:D1(){ }virtual void f() const{cout<<"B";}};class D2: public D1 {public:virtual void f(){cout<<"C";}};void fun(Base &b){ b.f(); }int main(){Base b; D1 d1; D2 d2;fun(b);fun(d1);fun(d2);b.f();d1.f();d2.f();return 0;}

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完善程序，使其运行时的输出结果如下：f1 function of derivef2 function of basef4 function of base#include using namespace std;class base{public:void f1(){cout<<"f1 function of base"<< endl; }virtual void f2(){cout<<"f2 function of base "<< endl; }void f4(){cout<<"f4 function of base "<f1();p->f2();p->f4();return 0;}

请将如下程序补充完整，使程序的输出结果如下：Derived::Print: 5Derived destructorBase destructor源程序清单：#include using namespace std;class BaseClass{public:~BaseClass();virtual void Print();};BaseClass::~BaseClass(){cout<< "Base destructor" << endl; }void BaseClass::Print(){cout << "BaseClass::Print" << endl;}class Derived:BaseClass{public:Derived();~Derived();void Print();private:int p;};Derived::Derived(){p =;}Derived::~Derived() {cout << "Derived destructor" << endl;delete p;}void Derived::Print(){cout << "Derived::Print: " <<p<< endl;}void fun(BaseClass* b) {b->Print();delete b;}int main() {BaseClass *ptr = ;fun(ptr);return 0;}

请改正程序中的错误（在对应空处写出错误所在行的完整一行，分号不写），使程序的输出结果如下：BaseClassDerived1Derived2#include using namespace std;class BaseClass {public:/ Error found【1】/void Print() const;};void BaseClass::Print() const {cout << "BaseClass" << endl;}/ Error found【2】/class Derived1::BaseClass{ public:void Print() const;};void Derived1::Print() const {cout << "Derived1" << endl;}class Derived2: public Derived1 {public:void Print() const;};void Derived2::Print() const {cout << "Derived2" << endl;}void Print(BaseClass &p) {/ Error found【3】/p->Print();}int main() {BaseClass b; Derived1 d1; Derived2 d2;Print(b); Print(d1); Print(d2);return 0;}

虚函数声明一个Shape基类，在此基础上公有派生出矩形Rectangle类和圆Circle类，二者都有函数GetArea()计算对象的面积，利用矩形类公有派生一个正方形Square类。具体要求如下：（1） Shape基类有以下公有成员：构造函数，函数体为空float GetArea()：虚函数，其返回值为-1void Print()：虚函数，函数体为空（2） Rectangle类的公有成员为：构造函数float GetArea()：计算矩形的面积void Print()：输出面积和长、宽私有成员为：float width：矩形的宽float length：矩形的长（3） Circle类的公有成员为：构造函数float GetArea()：计算圆的面积void Print()：输出面积和半径私有成员为：float radius：圆的半径（4） Square类的公有成员为：构造函数（5）主函数中通过Shape指针sp来实现对其他派生类对象的操作。