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  1. #include <utility>
  2. using namespace std;
  3.  
  4. template <char ... C>
  5. struct string_literal {
  6.     typedef string_literal type;
  7.     static constexpr const char value[sizeof...(C)] = {C...};
  8.     constexpr operator const char* (void) const {
  9.         return value;
  10.     }
  11. };
  12. template <char ... C>
  13. constexpr const char string_literal<C...>::value[sizeof...(C)];
  14.  
  15. template <unsigned N, const char (&S) [N], typename U>
  16. struct selector;
  17.  
  18. template <unsigned N, const char (&S) [N], unsigned ...I>
  19. struct selector<N, S, index_sequence<I...>> {
  20.     using type = string_literal<S[I]...>;
  21. };
  22.  
  23. template <unsigned N, const char (&S) [N]>
  24. struct make_string_literal {
  25.     using type = typename selector<N, S, make_index_sequence<N>>::type;
  26. };
  27.  
  28. template <unsigned N>
  29. constexpr auto size(const char (&s) [N]) {
  30.     return N;
  31. }
  32.  
  33. extern constexpr char value[] = "test";
  34. constexpr auto literal = make_string_literal<size(value), value>::type{};
  35.  
  36. #include <iostream>
  37. #include <typeinfo>
  38. int main() {
  39. 	std::cout << typeid(literal).name() << '=' << literal << std::endl;
  40. 	std::cout << typeid(value).name() << '=' << value << std::endl;
  41. 	return 0;
  42. }
Success #stdin #stdout 0s 3412KB
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stdin
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Standard input is empty
stdout
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14string_literalIJLc116ELc101ELc115ELc116ELc0EEE=test
A5_c=test
https://ideone.com/uKP2qj
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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