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  1. #include <iostream>
  2. #include <string>
  3. using namespace std;
  4.  
  5. template <typename T> class B;     //forward declare
  6.  
  7. template <typename T>
  8. class A
  9. {
  10.     T valuea;
  11. public:
  12.     A(){};
  13.     T getValuea()
  14.     {
  15.         return valuea;
  16.     }
  17.  
  18.     void setValuea(T x)
  19.     {
  20.         valuea = x;
  21.     }
  22.     A(const A &x)
  23.     { 
  24.         valuea = x.valuea; 
  25.     }
  26.  
  27.     friend class B<T>;     //A<int> is a friend of B<int> 
  28. };
  29.  
  30. template <typename T>
  31. class B : A<T>
  32. {
  33.     T valueb;
  34. public:
  35.     using A<T>::setValuea;
  36.     using A<T>::getValuea;
  37.     B(){};
  38.     T getValueb()
  39.     {
  40.         return valueb;
  41.     }
  42.     void setValueb(T x)
  43.     {
  44.         valueb = x;
  45.     }
  46.     B(const B &x)
  47.     {
  48.         valueb = x.valueb;
  49.         this->valuea = x.valuea;
  50.     }
  51. };
  52.  
  53. struct Date
  54. {
  55.     int day;
  56.     int month;
  57.     int year;
  58.  
  59.     friend ostream& operator << (ostream& os, const Date& date)
  60.     {
  61.     	return os << "Day: " << date.day << ", Month: " << date.month << ", Year: " << date.year << " ";
  62.     }
  63. };
  64.  
  65. int main()
  66. {
  67.     B<float> b;
  68.     b.setValuea(1.34);
  69.     b.setValueb(3.14);
  70.  
  71.     cout << "b.setValuea(1.34): " << b.getValuea() << endl
  72.         << "b.setValueb(3.14): " << b.getValueb() << endl;
  73.  
  74.     B<int> a;
  75.     a.setValuea(1);
  76.     a.setValueb(3);
  77.  
  78.     cout << "a.setValuea(1): " << a.getValuea() << endl
  79.         << "a.setValueb(3): " << a.getValueb() << endl;
  80.  
  81.     B<char> y;
  82.     y.setValuea('a');
  83.     y.setValueb('c');
  84.  
  85.     cout << "y.setValuea('a'): " << y.getValuea() << endl
  86.         << "y.setValueb('c'): " << y.getValueb() << endl;
  87.  
  88.     B<string> u;
  89.     u.setValuea("good");
  90.     u.setValueb("morning");
  91.  
  92.     cout << "u.setValuea(good): " << u.getValuea() << endl
  93.         << "u.setValueb(morning): " << u.getValueb() << endl;
  94.  
  95.     B<Date> p;
  96.     p.setValuea({ 27, 10, 2014 });
  97.     p.setValueb({ 2, 11, 2014 });
  98.  
  99.     cout << "p.setValuea({ 27, 10, 2014 }): " << p.getValuea() << endl
  100.          << "p.setValueb({ 2, 11, 2014 }):  " << p.getValueb() << endl;
  101.  
  102.  
  103.     system("Pause");
  104.     return 0;
  105. }
  106.  
  107.  
Success #stdin #stdout #stderr 0s 3476KB
comments ()
stdin 
Standard input is empty
stdout 
b.setValuea(1.34): 1.34
b.setValueb(3.14): 3.14
a.setValuea(1): 1
a.setValueb(3): 3
y.setValuea('a'): a
y.setValueb('c'): c
u.setValuea(good): good
u.setValueb(morning): morning
p.setValuea({ 27, 10, 2014 }): Day: 27, Month: 10, Year: 2014 
p.setValueb({ 2, 11, 2014 }):  Day: 2, Month: 11, Year: 2014
stderr 
sh: Pause: not found
https://ideone.com/ehio6Q
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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