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  1. #include <iostream>
  2. #include <iterator>
  3. #include <typeinfo>
  4. #include <vector>
  5.  
  6. template <class FwdIt>
  7. void test_func(FwdIt first) {
  8.     using FwdIt_vt = typename std::iterator_traits<FwdIt>::value_type;
  9.     using Declt_vt = decltype(*first);
  10.  
  11.     std::cout << "iterator_traits: " << typeid(FwdIt_vt).name() << '\n';
  12.     std::cout << "decltype: " << typeid(Declt_vt).name() << '\n';
  13. }
  14.  
  15. int main(int argc, char* args[]) {
  16. 	std::cout << "std::vector<int>::iterator" << '\n';
  17.     std::vector<int> ints;
  18.     test_func(ints.begin());
  19.     std::cout << '\n';
  20.  
  21.     std::cout << "std::vector<bool>::iterator" << '\n';
  22.     std::vector<bool> bools;
  23.     test_func(bools.begin());
  24.     std::cout << '\n';
  25. }
Success #stdin #stdout 0s 3296KB
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stdin
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Standard input is empty
stdout
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std::vector<int>::iterator
iterator_traits: i
decltype: i

std::vector<bool>::iterator
iterator_traits: b
decltype: St14_Bit_reference
https://ideone.com/92jZXY
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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