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  1. #include <iostream>
  2. #include <type_traits>
  3.  
  4. // Array for reference.  Unused except for grabbing type.
  5. int array[5];
  6.  
  7. // Array's type.  Type is: int (*)[5]
  8. using A = decltype(array);
  9.  
  10. // Function that takes pointer-to-array as argument.
  11. // Should use templates, really, or a typedef if array definition will never change.
  12. int sum(int (*arr)[5]) {
  13.     int ret = 0;
  14.     for (int i = 0; i < 5; i++) { ret += (*arr)[i]; }
  15.     return ret;
  16. }
  17.  
  18. // Function that takes reference-to-array as argument.
  19. // Should use templates, really, or a typedef if array definition will never change.
  20. int refsum(int (&arr)[5]) { return sum(&arr); }
  21.  
  22. // It's not that much cleaner, but templates help a lot here.
  23. template<typename T, size_t N, typename TN = T[N]>
  24. int temsum(T (*arr)[N]) {
  25. 	static_assert(std::is_same<T, int>::value && (N == 5));
  26. 	static_assert(std::is_same<TN*, A*>::value);
  27. 	return sum(arr);
  28. }
  29.  
  30. // Function that returns pointer-to-array.
  31. // Looks awful.
  32. int (*create())[5] {
  33. 	// Don't do this outside of throwaway examples. ^_^
  34.     int (*arr)[5] = reinterpret_cast<int(*)[5]>(new int[5]);
  35.     for (int i = 1; i < 6; i++) { (*arr)[i - 1] = i * i; }
  36.     return arr;
  37. }
  38.  
  39. // This is the only sane way to work with pointers-to-array, since a typedef uses normal syntax.
  40. void destroy(A* arr) {
  41. 	// Don't do this, either.
  42. 	delete[] reinterpret_cast<int*>(arr);
  43. }
  44.  
  45. int main() {
  46. 	// Clean way to use pointer-to-array: Use the typedef.
  47.     A* arr = create();
  48.     int sum1 = sum(arr);
  49.     int sum2 = refsum(*arr);
  50.     int sum3 = temsum(arr);
  51.  
  52.     std::cout << sum1 << ' ' << sum2 << ' ' << sum3 << '\n';
  53.  
  54.     destroy(arr);    
  55. }
Success #stdin #stdout 0s 5400KB
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Standard input is empty
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55 55 55
https://ideone.com/nVDnRz
language:
C++14 (gcc 8.3)
created:
2 years ago
visibility:
secret

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