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纯虚函数继承并使用new动态生成失败了

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[已解决问题] 解决于 2020-05-01 13:48

编译会出现这种问题:
[Error] invalid new-expression of abstract class type 'Circle'

[Note] because the following virtual functions are pure within 'Square':

[Note] virtual void Shape::getnum()

等等总共相似的有五种

复制代码
  1 #include <iostream>
  2 
  3 using namespace std;
  4 
  5 class Shape
  6 {
  7     public:
  8         virtual void getnum()=0;
  9         virtual double printArea()=0;
 10         virtual void printName()=0;
 11     
 12 };
 13 
 14 class Circle:public Shape
 15 {
 16     private:
 17         double r;
 18     public:
 19         void getnum(double a, double b, double c){this->r=a;}
 20         double printArea(){return 3.14159*r*r;}
 21         void printName()
 22         {
 23             cout<<"圆:半径="<<r<<",面积:"<<printArea()<<endl;
 24         }
 25 };
 26 
 27 class Square:public Shape
 28 {
 29     private:
 30         double  a;
 31     public:
 32         void getnum(double a, double b, double c){this->a=a;}
 33         double printArea(){return a*a; }
 34         void printName()
 35         {
 36             cout<<"正方形:边长="<<a<<",面积="<<printArea()<<endl;
 37         }
 38 };
 39 
 40 class Rectangle:public Shape
 41 {
 42     private:
 43         double a,b;
 44     public:
 45         void getnum(double a, double b, double c){this->a=a;this->b=b;}
 46         double printArea(){return a*b;}
 47         void printName()
 48         {
 49             cout<<"长方形:长="<<a<<",宽="<<b<<",面积="<<printArea()<<endl;
 50         }
 51 };
 52 
 53 class Trapezoid:public Shape
 54 {
 55     private:
 56         double a,b,c;
 57     public:
 58         void getnum(double a, double b, double c)
 59         {
 60             this->a=a;
 61             this->b=b;
 62             this->c=c;
 63         }
 64         double printArea(){return (a+b)*c*0.5;}
 65         void printName()
 66         {
 67             cout<<"梯形:上底="<<a<<",宽="<<b<<",高="<<c<<",面积="<<printArea()<<endl;
 68         }
 69 };
 70 
 71 class Triangle:public Shape
 72 {
 73     private:
 74         double a,b;
 75     public:
 76         void getnum(double a, double b, double c){this->a=a;this->b=b;}
 77         double printArea(){return a*b*0.5;}
 78         void printName()
 79         {
 80             cout<<"三角形:底边="<<a<<",高="<<b<<",面积="<<printArea()<<endl;
 81         }
 82 };
 83 
 84 int main()
 85 {
 86     double r,x,a,b,m,n,l,s,h;
 87     double area=0.0;
 88     cin>>r>>x>>a>>b>>m>>n>>l>>s>>h;
 89     Shape *p[5];
 90     p[0]=new Circle;
 91     p[1]=new Square;
 92     p[2]=new Rectangle;
 93     p[3]=new Trapezoid;
 94     p[4]=new Triangle;
 95     p[0]->getnum(r);
 96     p[1]->getnum(x);
 97     p[2]->getnum(a,b);
 98     p[3]->getnum(m,n,l);
 99     p[4]->getnum(s,h);
100     for(int i=0;i<5;i++)
101     {
102         p[i]->printName();
103         area+=p[i]->printArea();
104     }
105     cout<<"总面积:"<<area<<endl;
106     return 0;
107 }
复制代码
Conan-jine的主页 Conan-jine | 小虾三级 | 园豆:1272
提问于:2020-04-29 23:52
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最佳答案
0

该问题貌似是纯虚函数继承方面的问题,把getnum的功能转化为构造函数就可以解决问题了,但是我不是很了解,为啥我这样写会出问题

Conan-jine | 小虾三级 |园豆:1272 | 2020-05-01 13:48
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