检查这个代码#include<iostream> using namespace std; class Shape { protected: int r; public: Shape(int r); virtual double surfaceArea()=0; virtual double volume()=0; }; Shape::Shape(int r):r(r){ } class Ball:public Shape{ public: Ball(int r); double surfaceArea()override; double volume ()override; }; Ball::Ball(int r):Shape(r){ } double Ball::surfaceArea(){ return 4*3.14*r*r; } double Ball::volume(){ return 4.0/3*3.14*r*r*r; } class Cylinder:public Shape{ private: int height; public: Cylinder(int r,int height); double surfaceArea()override; double volume()override; };

代码没有结束，缺少最后的括号和分号。另外，在Cylinder类的构造函数中，应该调用父类构造函数来初始化Shape类中的r成员变量。正确的代码如下：

#include<iostream>
using namespace std;

class Shape {
protected:
    int r;
public:
    Shape(int r);
    virtual double surfaceArea()=0;
    virtual double volume()=0;
};

Shape::Shape(int r):r(r){}

class Ball:public Shape{
public:
    Ball(int r);
    double surfaceArea()override;
    double volume ()override;
};

Ball::Ball(int r):Shape(r){}

double Ball::surfaceArea(){
    return 4*3.14*r*r;
}

double Ball::volume(){
    return 4.0/3*3.14*r*r*r;
}

class Cylinder:public Shape{
private:
    int height;
public:
    Cylinder(int r,int height);
    double surfaceArea()override;
    double volume()override;
};

Cylinder::Cylinder(int r,int height):Shape(r),height(height){}

double Cylinder::surfaceArea(){
    return 2*3.14*r*r+2*3.14*r*height;
}

double Cylinder::volume(){
    return 3.14*r*r*height;
}