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  1. #include <iostream>
  2. #include <type_traits>
  3. #include <cstdint>
  4.  
  5. int GetId()
  6. {
  7.   static int id = 0;
  8.   id++;
  9.   return id;
  10. }
  11.  
  12. template <class T>
  13. struct TypeId
  14. {
  15.   typedef T type;
  16.   static const int id;
  17. };
  18.  
  19.  
  20. template <class T>
  21. struct TypeId<T*>
  22. {
  23.   typedef T* type;
  24.   static const int id = -1;
  25. };
  26.  
  27.  
  28. //static 
  29. template <class T>
  30. const int TypeId<T>::id = GetId();
  31.  
  32.  
  33. class A
  34. {
  35. };
  36.  
  37. class B
  38. {
  39. };
  40.  
  41.  
  42. class C
  43. {
  44.   public:
  45.     C()
  46.     {
  47.       std::cout << "id of this for C = "   << TypeId<std::remove_pointer<decltype(this)>::type>::id   << std::endl;
  48.     }
  49. };
  50.  
  51.  
  52. template<class T>
  53. void foo(T & val)
  54. {
  55.     std::cout << "foo, id of T = " << TypeId<T>::id << std::endl;
  56. }
  57.  
  58.  
  59. int main(int argc, char* argv[])
  60. {
  61.     int n = 0;
  62.     foo(n);
  63.     int* pn = &n;
  64.     foo(pn);
  65.     char ch = 'a';
  66.     foo(ch);
  67.     char* pch = &ch;
  68.     foo(pch);
  69.  
  70.  
  71.     std::cout << "id of A = "    << TypeId<A>::id    << std::endl;
  72.     std::cout << "id of C = "    << TypeId<C>::id    << std::endl;
  73.     std::cout << "id of A = "    << TypeId<A>::id    << std::endl;
  74.     std::cout << "id of B = "    << TypeId<B>::id    << std::endl;
  75.     std::cout << "id of C = "    << TypeId<C>::id    << std::endl;
  76.     std::cout << "id of int = "  << TypeId<int>::id  << std::endl;
  77.     std::cout << "id of int32_t=" << TypeId<int32_t>::id  << std::endl;
  78.     std::cout << "id of int16_t=" << TypeId<int16_t>::id  << std::endl;
  79.     std::cout << "id of int* = " << TypeId<int*>::id << std::endl;
  80.     std::cout << "id of A* = "   << TypeId<A*>::id   << std::endl;
  81.  
  82.     return 0;
  83. }
  84.  
Success #stdin #stdout 0s 3456KB
comments (?)
stdin 
Standard input is empty
stdout 
foo, id of T = 4
foo, id of T = -1
foo, id of T = 6
foo, id of T = -1
id of A = 2
id of C = 1
id of A = 2
id of B = 3
id of C = 1
id of int = 4
id of int32_t=4
id of int16_t=5
id of int* = -1
id of A* = -1
https://ideone.com/Ao4lc0
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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