修改这段代码使其可以运行：#include <iostream> #include <cmath> using namespace std; class Shape{ public: virtual double GetArea()=0; virtual double GetPerimeter()=0; }; class Circle:public Shape{ double r1; public: Circle(double _r):r1(_r){} double GetArea(){ return 3.14*r1*r1; } double GetPerimeter(){ return 2*3.14*r1; } }; class Outside:public Shape{ double r2; public: Outside(double _r):r2(_r){} double GetArea(){ return 4*r2*r2; } double GetPerimeter(){ return 8*r2; } }; class Inside:public Shape{ double r3; public: Inside(double _r):r3(_r){} double d=sqrt(2*r3*r3); double GetArea(){ return d*d; } double GetPerimeter(){ return 4*d; } }; int main(){ Shape *C=new Circle(2.0); cout<<C->GetArea()<<" "<<C->GetPerimeter<<endl; Shape *O=new Outside(2.0); cout<<O->GetArea()<<" "<<O->GetPerimeter<<endl; Shape *I=new Inside(2.0); cout<<I->GetArea()<<" "<<I->GetPerimeter<<endl; delete C; delete O; delete I; return 0; }

已修改的代码如下：

#include <iostream> 
#include <cmath> 

using namespace std; 

class Shape {
public:
    virtual double GetArea()=0; 
    virtual double GetPerimeter()=0; 
}; 

class Circle:public Shape { 
    double r1; 
public: 
    Circle(double _r):r1(_r){} 
    double GetArea(){ 
        return 3.14*r1*r1; 
    } 
    double GetPerimeter(){ 
        return 2*3.14*r1; 
    } 
}; 

class Outside:public Shape { 
    double r2; 
public: 
    Outside(double _r):r2(_r){} 
    double GetArea(){ 
        return 4*r2*r2; 
    } 
    double GetPerimeter(){ 
        return 8*r2; 
    } 
}; 

class Inside:public Shape { 
    double r3; 
public: 
    Inside(double _r):r3(_r){} 
    double GetArea(){ 
        double d=sqrt(2*r3*r3); 
        return d*d; 
    } 
    double GetPerimeter(){ 
        double d=sqrt(2*r3*r3); 
        return 4*d; 
    } 
}; 

int main() { 
    Shape *C=new Circle(2.0); 
    cout<<C->GetArea()<<" "<<C->GetPerimeter()<<endl; 

    Shape *O=new Outside(2.0); 
    cout<<O->GetArea()<<" "<<O->GetPerimeter()<<endl; 

    Shape *I=new Inside(2.0); 
    cout<<I->GetArea()<<" "<<I->GetPerimeter()<<endl; 

    delete C; 
    delete O; 
    delete I; 

    return 0; 
}

主要问题是 Inside 类中的 `d` 定义在类的外部，需要在 `GetArea()` 和 `GetPerimeter()` 中重新定义。此外，在输出 `C->GetPerimeter()` 时，应该加上括号。