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  1. #include <algorithm>
  2. #include <cctype>
  3. #include <cassert>
  4. #include <set>
  5. #include <string>
  6.  
  7. struct icase_less {
  8.   bool operator()(const std::string& x, const std::string& y) const {
  9.     // для однобайтных кодировок без учёта диграфов типа эсцета - сойдёт
  10.     return std::lexicographical_compare(
  11.       std::begin(x), std::end(x),
  12.       std::begin(y), std::end(y),
  13.       [](char a, char b)->bool { return std::toupper(a) < std::toupper(b); } );
  14.   }
  15. };
  16.  
  17. template<class LESS>
  18. struct dependent_equal {
  19.  LESS less;
  20.  template<class X, class Y>
  21.  bool operator()(X&& x, Y&& y) const {
  22.    return !less(std::forward<X>(x), std::forward<Y>(y))
  23.        && !less(std::forward<Y>(y), std::forward<X>(x));
  24.  }
  25. };
  26.  
  27. int main() {
  28.   using icase_multiset = std::multiset<std::string, icase_less>;
  29.   icase_multiset xx = { "alfa", "beta", "Beta", "BETA", "gamma" };
  30.   icase_multiset yy = { "alfa", "Beta", "BETA", "BeTa", "gamma" };
  31.   //                            <--------------------> класс эквивалентности "beta"
  32.  
  33.   using icase_equal = dependent_equal<icase_less>;
  34.   // выполняем попарное сравнение
  35.   assert( std::equal(std::begin(xx), std::end(xx),
  36.                      std::begin(yy), std::end(yy),
  37.                      icase_equal()));
  38.   // попарное сравнение без "без учёта регистра" не прокатит
  39.   assert(!std::equal(std::begin(xx), std::end(xx),
  40.                      std::begin(yy), std::end(yy)));
  41. }
  42.  
Success #stdin #stdout 0s 16064KB
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https://ideone.com/fbUpn9
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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