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  1. #include <iostream>
  2. #include <string>
  3.  
  4. using namespace std;
  5.  
  6. class Polygon 
  7. {
  8.   protected:
  9.     int width, height;
  10.   public:
  11.     Polygon (int a, int b) : width(a), height(b) {}
  12.     virtual ~Polygon() { }
  13.     virtual int area() = 0;
  14. };
  15.  
  16. class Output 
  17. {
  18.   private:
  19.     std::string myString;
  20.  
  21.   public:
  22.     Output() {    }
  23.  
  24.     Output(const string& s) : myString(s) {   }
  25.  
  26.     // This seems to work, but ther core dump happens right afterwards.
  27.     virtual ~Output() {    }
  28.     virtual int area() = 0;
  29.     void print () {
  30.       cout << myString << this->area() << '\n';
  31.     }
  32. };
  33.  
  34.  
  35.  
  36. class Rectangle: public Polygon, public Output 
  37. {
  38.   public:
  39.     Rectangle (int a, int b) : Polygon(a,b), Output{"A Rectangle's area is: "} {}
  40.     int area () {
  41.      return width*height;
  42.    }
  43. };
  44.  
  45. class Triangle: public Polygon, public Output  
  46. {
  47.   public:
  48.     Triangle (int a, int b) : Polygon{a,b}, Output{"A Triangle's area is: "} {}
  49.     int area ()
  50.       { return width*height/2; }
  51. };
  52.  
  53. int main () 
  54. {
  55.   Output * ptr1 = new Rectangle(4,5);
  56.   Output * ptr2 = new Triangle(4,5);
  57.  
  58.   ptr1->print();
  59.   ptr2->print();
  60.  
  61.   // Causes core dump.  
  62.   delete ptr1;
  63.   delete ptr2;
  64.  
  65.   return 0;
  66. }
Success #stdin #stdout 0s 3476KB
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stdin
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Standard input is empty
stdout
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A Rectangle's area is: 20
A Triangle's area is: 10
https://ideone.com/Bug1v5
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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