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  1. #include <iostream>
  2. #include <utility>
  3. #include <cstring>
  4.  
  5. class S {
  6. public:
  7.   S(const char* s) : l(std::strlen(s)), s(new char[l+1]) { std::strcpy(this->s, s); }
  8.   S(const S& o) : l(o.l), s(new char[l+1]) { strcpy(s, o.s); }
  9.   S& operator = (S o)
  10.   {
  11.      swap(o);
  12.      return *this;
  13.   }
  14.   ~S() { delete [] s; }
  15.   void swap(S& o)
  16.   {
  17.      using std::swap;
  18.      swap(l, o.l);
  19.      swap(s, o.s);
  20.   }
  21.   friend std::ostream& operator << (std::ostream& os, const S& s) { return os << s.s; }
  22. private:
  23.   size_t l;
  24.   char* s;
  25. };
  26.  
  27. class A {
  28. public:
  29.   A(const char* s) : s(s) {}
  30.   A(const A& o) : s(o.s) {}
  31.   A& operator = (A o)
  32.   {
  33.      swap(o);
  34.      return *this;
  35.   }
  36.   virtual ~A() {}
  37.   void swap(A& o)
  38.   {
  39.      s.swap(o.s);
  40.   }
  41.   friend std::ostream& operator << (std::ostream& os, const A& a) { return os << a.s; }
  42.  
  43. private:
  44.   S s;
  45. };
  46.  
  47. template <int N>
  48. class B : public virtual A {
  49. public:
  50.   B(const char* sA, const char* s) : A(sA), s(s) {}
  51.   B(const B& o) : A(o), s(o.s) {}
  52.   B& operator = (B o)
  53.   {
  54.      swap(o);
  55.      return *this;
  56.   }
  57.   virtual ~B() {}
  58.   void swap(B& o)
  59.   {
  60.      A::swap(o);
  61.      s.swap(o.s);
  62.   }
  63.   friend std::ostream& operator << (std::ostream& os, const B& b) 
  64.   { return os << (const A&)b << ',' << b.s; }
  65.  
  66. private:
  67.   S s;
  68. };
  69.  
  70. class D : public B<1>, public B<2> {
  71. public:
  72.   D(const char* sA, const char* sB1, const char* sB2, const char* s) 
  73.    : A(sA), B<1>(sA, sB1), B<2>(sA, sB2), s(s) 
  74.   {}
  75.   D(const D& o) : A(o), B<1>(o), B<2>(o), s(o.s) {}
  76.   D& operator = (D o)
  77.   {
  78.      swap(o);
  79.      return *this;
  80.   }
  81.   virtual ~D() {}
  82.   void swap(D& o)
  83.   {
  84.      B<1>::swap(o); // calls A::swap(o); A::s changed to o.s
  85.      B<2>::swap(o); // calls A::swap(o); A::s returned to original value...
  86.      s.swap(o.s);
  87.   }
  88.   friend std::ostream& operator << (std::ostream& os, const D& d) 
  89.   { 
  90.      // prints A::s twice...
  91.      return os 
  92. 	<< (const B<1>&)d << ',' 
  93. 	<< (const B<2>&)d << ',' 
  94.         << d.s;
  95.   }
  96. private:
  97.   S s;
  98. };
  99.  
  100. int main() {
  101.    D x("ax", "b1x", "b2x", "x");
  102.    D y("ay", "b1y", "b2y", "y");
  103.    std::cout << x << "\n" << y << "\n";
  104.    x = y;
  105.    std::cout << x << "\n" << y << "\n";
  106. }
  107.  
  108.  
Success #stdin #stdout 0s 3068KB
comments (?)
stdin
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Standard input is empty
stdout
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ax,b1x,ax,b2x,x
ay,b1y,ay,b2y,y
ax,b1y,ax,b2y,y
ay,b1y,ay,b2y,y
https://ideone.com/HrVBC
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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