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  1. #include <vector>
  2. #include <new>
  3.  
  4. template <class t>//templated class
  5. class Square
  6. {
  7. public:
  8.     t side;
  9.     //inline constructor
  10.     Square(t side){ this->side = side; }
  11.  
  12.     ~Square() { }
  13.  
  14.     t getSide();
  15. };
  16.  
  17.  
  18. int main()
  19. {
  20.     const unsigned num_elements = 4;
  21.  
  22.     {
  23.         // manually:
  24.         void* raw_memory = operator new(sizeof(Square<double>) * num_elements);
  25.         Square<double>* sqr = static_cast<Square<double>*>(raw_memory);
  26.  
  27.         // construct each of the 4 squares:
  28.         for (unsigned i = 0; i < num_elements; ++i)
  29.             new (sqr + i) Square<double>(i*3.14);
  30.  
  31.         // use the Squares here
  32.  
  33.         // then, what was constructed must be destructed:
  34.         for (unsigned i = 0; i < num_elements; ++i)
  35.             (sqr + i)->~Square<double>();
  36.  
  37.         // and the memory deallocated.
  38.         operator delete(sqr);
  39.     }
  40.  
  41.     //using std::vector:
  42.     {
  43.         std::vector<Square<double>> sqr;
  44.         for (unsigned i = 0; i < num_elements; ++i)
  45.             sqr.emplace_back(i*3.14);
  46.  
  47.         // use the squares here...
  48.  
  49.         // then the objects are automatically destructed and
  50.         // memory freed when sqr goes out of scope.
  51.     }
  52. }
Success #stdin #stdout 0s 3468KB
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https://ideone.com/69kk62
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
secret

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