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  1. #include <iostream>
  2. #include <string>
  3. #include <utility>
  4. #include <vector>
  5.  
  6. namespace {
  7.  
  8. template <typename T>
  9. class MyAllocator {
  10.  public:
  11.   using value_type = T;
  12.  
  13.   MyAllocator(std::string iType) : _type(std::move(iType)) {}
  14.  
  15.   T* allocate(const std::size_t iNo) { return new T[iNo]; }
  16.   void deallocate(T* iPtr, const std::size_t) { delete[] iPtr; }
  17.  
  18.   constexpr bool operator!=(const MyAllocator& oth) const {
  19.     return _type != oth._type;
  20.   }
  21.  
  22.   const std::string& getType() const noexcept { return _type; }
  23.  
  24.  private:
  25.   std::string _type;
  26. };
  27.  
  28. using MyString =
  29.     std::basic_string<char, std::char_traits<char>, MyAllocator<char>>;
  30.  
  31. }  // anonymous namespace
  32.  
  33. int main(int, char**) {
  34.   ::MyString str1(::MyAllocator<char>("ForStr1"));
  35.   ::MyString str2(::MyAllocator<char>("ForStr2"));
  36.   ::MyString str3(::MyAllocator<char>("ForStr3"));
  37.  
  38.   std::vector<::MyString> aVector;
  39.   aVector.reserve(1024);
  40.  
  41.   aVector.push_back(str1);
  42.   aVector.push_back(str2);
  43.  
  44.     std::cout << "[0]: " << aVector[0].get_allocator().getType() << "\n"
  45.               << "[1]: " << aVector[1].get_allocator().getType() << "\n";
  46.  
  47.  
  48.   aVector.insert(aVector.begin(), str3);
  49.  
  50.   const auto& type0 = aVector[0].get_allocator().getType();
  51.   const auto& type1 = aVector[1].get_allocator().getType();
  52.   const auto& type2 = aVector[2].get_allocator().getType();
  53.  
  54.   std::cout << "[0]: " << type0 << "\n"
  55.             << "[1]: " << type1 << "\n"
  56.             << "[2]: " << type2 << "\n";
  57.  
  58.   return 0;
  59. }
  60.  
Success #stdin #stdout 0s 4248KB
comments (?)
stdin
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Standard input is empty
stdout
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[0]: ForStr1
[1]: ForStr2
[0]: ForStr1
[1]: ForStr2
[2]: ForStr2
https://ideone.com/RcEycq
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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