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  1. #include <iostream>
  2. #include <vector>
  3. #include <map>
  4. #include <type_traits>
  5.  
  6. template <typename> struct is_pair : std::false_type {};
  7. template <typename T, typename U> struct is_pair<std::pair<T, U>> : std::true_type {};
  8.  
  9. namespace extract
  10. {
  11.     template <typename Iter>
  12.     auto
  13.     e(Iter it)
  14.     -> typename std::enable_if<is_pair<typename std::iterator_traits<Iter>::value_type>::value,
  15.         decltype(it->second)>::type
  16.     {
  17.         return it->second;
  18.     }
  19.  
  20.     template <typename Iter>
  21.     auto
  22.     e(Iter it)
  23.     -> typename std::enable_if<!is_pair<typename std::iterator_traits<Iter>::value_type>::value,
  24.         decltype(*it)>::type
  25.     {
  26.         return *it;
  27.     }
  28.  
  29. }
  30.  
  31. template<typename Iterator>
  32. void print(Iterator begin, Iterator end)
  33. {
  34.     while (begin != end)
  35.     {
  36.         std::cout << extract::e(begin) << std::endl;
  37.         ++begin;
  38.     }
  39. }
  40.  
  41. int main()
  42. {
  43.     std::vector<int> v(3, 1);
  44.     std::map<int, int> m = {{0, 10}, {1, 11}, {2, 12}};
  45.  
  46.     print(v.begin(), v.end());
  47.     print(m.begin(), m.end());
  48.  
  49.     return 0;
  50. }
  51.  
Success #stdin #stdout 0s 3476KB
comments (?)
stdin 
Standard input is empty
stdout 
1
1
1
10
11
12
https://ideone.com/CFZk8o
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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