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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. template< class T > struct my_remove_reference      {typedef T type;};
  5. template< class T > struct my_remove_reference<T&>  {typedef T type;};
  6. template< class T > struct my_remove_reference<T&&> {typedef T type;};
  7.  
  8. template <typename T>
  9. typename my_remove_reference<T>::type&& my_move(T&& arg)
  10. {
  11.     return static_cast<typename my_remove_reference<T>::type&&>(arg);
  12. }
  13.  
  14. struct S
  15. {
  16.     int *ptr = nullptr;
  17.  
  18.     S() { cout << "S() default constructor, ptr = " << ptr << endl; }
  19.     S(int *p) : ptr(p) { cout << "S(int*) constructor, ptr = " << ptr << endl; }
  20. };
  21.  
  22. class MoveTester
  23. {
  24. private:
  25.     int *m_ptr = nullptr;
  26.  
  27. public:
  28.     MoveTester() { cout << "MT() default constructor" << endl; }
  29.     MoveTester(const MoveTester &) = delete;
  30.     MoveTester(MoveTester&& src) : m_ptr(src.m_ptr) { src.m_ptr = nullptr; cout << "MT(MT&&) move constructor" << endl; }
  31.  
  32.     MoveTester(int *ptr) : m_ptr(ptr) { cout << "MT(int*) constructor" << endl; }
  33.     MoveTester(S&& src) : m_ptr(src.ptr) { src.ptr = nullptr; cout << "MT(S&&) move constructor" << endl; }
  34.  
  35.     MoveTester& operator=(const MoveTester &) = delete;
  36.     MoveTester& operator=(MoveTester&& rhs) { m_ptr = rhs.m_ptr; rhs.m_ptr = nullptr; cout << "MT::operator=(MT&&) move assignment" << endl; return *this; }
  37.     MoveTester& operator=(int *rhs) { m_ptr = rhs; cout << "MT::operator=(int*) copy assignment" << endl; return *this; }
  38.     MoveTester& operator=(S&& src) { m_ptr = src.ptr; src.ptr = nullptr; cout << "MT::operator=(S&&) move assignment" << endl; return *this; }
  39.  
  40.     void display(const char *name) const { cout << name << ".m_ptr = " << m_ptr << endl; }
  41. };
  42.  
  43. int* int_to_ptr(intptr_t value) { return reinterpret_cast<int*>(value); }
  44.  
  45. int main()
  46. {
  47.     cout << "MoveTester mt1;" << endl;
  48.     MoveTester mt1;
  49.     mt1.display("mt1");
  50.  
  51.     cout << endl;
  52.  
  53.     cout << "MoveTester mt2 = int_to_ptr(12345);" << endl;
  54.     MoveTester mt2 = int_to_ptr(12345);
  55.     mt2.display("mt2");
  56.  
  57.     cout << endl;
  58.  
  59.     //MoveTester mt3 = mt2; // compiler error! Copy constructor is deleted
  60.     cout << "MoveTester mt3 = my_move(mt2);" << endl;
  61.     MoveTester mt3 = my_move(mt2);
  62.     mt2.display("mt2");
  63.     mt3.display("mt3");
  64.  
  65.     cout << endl;
  66.  
  67.     cout << "MoveTester mt4 = S();" << endl;
  68.     MoveTester mt4 = S();
  69.     mt4.display("mt4");
  70.  
  71.     cout << endl;
  72.  
  73.     cout << "MoveTester mt5 = S(int_to_ptr(67890));" << endl;
  74.     MoveTester mt5 = S(int_to_ptr(67890));
  75.     mt5.display("mt5");
  76.  
  77.     cout << endl;
  78.  
  79.     //mt1 = mt5; // compiler error! Copy assignment is deleted
  80.     cout << "mt1 = my_move(mt5);" << endl;
  81.     mt1 = my_move(mt5);
  82.     mt1.display("mt1");
  83.     mt5.display("mt5");
  84.  
  85.     cout << endl;
  86.  
  87.     cout << "mt1 = int_to_ptr(13579);" << endl;
  88.     mt1 = int_to_ptr(13579);
  89.     mt1.display("mt1");
  90.  
  91.     cout << endl;
  92.  
  93.     cout << "mt1 = S();" << endl;
  94.     mt1 = S();
  95.     mt1.display("mt1");
  96.  
  97.     cout << endl;
  98.  
  99.     cout << "mt1 = S(int_to_ptr(24680));" << endl;
  100.     mt1 = S(int_to_ptr(24680));
  101.     mt1.display("mt1");
  102.  
  103.     return 0;
  104. }
Success #stdin #stdout 0s 15240KB
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Standard input is empty
stdout
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MoveTester mt1;
MT() default constructor
mt1.m_ptr = 0

MoveTester mt2 = int_to_ptr(12345);
MT(int*) constructor
mt2.m_ptr = 0x3039

MoveTester mt3 = my_move(mt2);
MT(MT&&) move constructor
mt2.m_ptr = 0
mt3.m_ptr = 0x3039

MoveTester mt4 = S();
S() default constructor, ptr = 0
MT(S&&) move constructor
mt4.m_ptr = 0

MoveTester mt5 = S(int_to_ptr(67890));
S(int*) constructor, ptr = 0x10932
MT(S&&) move constructor
mt5.m_ptr = 0x10932

mt1 = my_move(mt5);
MT::operator=(MT&&) move assignment
mt1.m_ptr = 0x10932
mt5.m_ptr = 0

mt1 = int_to_ptr(13579);
MT::operator=(int*) copy assignment
mt1.m_ptr = 0x350b

mt1 = S();
S() default constructor, ptr = 0
MT::operator=(S&&) move assignment
mt1.m_ptr = 0

mt1 = S(int_to_ptr(24680));
S(int*) constructor, ptr = 0x6068
MT::operator=(S&&) move assignment
mt1.m_ptr = 0x6068
https://ideone.com/xpJl5h
language:
C++ (gcc 8.3)
created:
6 years ago
visibility:
public

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