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  1. #include <iostream>
  2.  
  3. template <class T>
  4. class A {
  5.   T d;
  6. public:
  7.   A(T a) : d(a) {}
  8.   template<class U, class V>
  9.   friend auto operator*(U& x, V& y) -> decltype(U::d * V::d);
  10. };
  11.  
  12. template<class T, class U>
  13. auto operator*(T& x, U& y) -> decltype(T::d * U::d)
  14. {
  15.   return x.d * y.d;
  16. }
  17.  
  18. int main()
  19. {
  20.   A<double> a(3.0);
  21.   A<int> b(5);
  22.  
  23.   std::cout << a * b << std::endl;
  24. }
Success #stdin #stdout 0s 3296KB
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15
https://ideone.com/WPhg2Q
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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