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  1. #include <type_traits>
  2. #include <stdexcept>
  3. #include <memory>
  4. #include <iostream>
  5.  
  6. struct T {
  7.    int val;
  8.    T() = delete;
  9.    T(int i) : val(i) {}
  10.    void* operator new[](std::size_t, std::size_t cnt, const T& t)
  11.    {
  12.        typedef std::aligned_storage<sizeof(t),
  13.                     std::alignment_of<T>::value>::type buf;
  14.        T* ptr = reinterpret_cast<T*>(new buf[cnt]);
  15.        std::uninitialized_fill_n(ptr, cnt, t);
  16.        return ptr;
  17.     }
  18. };
  19.  
  20. int main()
  21. {
  22.     T* a = new(100, T(7)) T[0]; // using zero is legal per 5.3.4/7
  23.  
  24.     std::cout << "a[0] = " << a[0].val << '\n'
  25.               << "a[1] = " << a[1].val << '\n'
  26.               << "a[98] = " << a[98].val << '\n'
  27.               << "a[99] = " << a[99].val << '\n';
  28.     delete[] a; // I know this won't call the 100 destructors, but it will free the 100 aligned_storages at least
  29. }
  30.  
Success #stdin #stdout 0s 2960KB
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stdin
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Standard input is empty
stdout
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a[0] = 7
a[1] = 7
a[98] = 7
a[99] = 7
https://ideone.com/iBW0z
language:
C++14 (gcc 8.3)
created:
13 years ago
visibility:
public

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