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  1. #include <iostream>
  2. #include <vector>
  3. using namespace std;
  4.  
  5. class X
  6. {
  7. public:
  8.  
  9.     std::vector<double> data;
  10.  
  11.     // Constructor1
  12.     X():
  13.     data(100000) // lots of data
  14.     {
  15.         cout << "X() called" << endl;
  16.     }
  17.  
  18.     // Constructor2
  19.     X(X const& other) // copy constructor
  20.         : data(other.data)   // duplicate all that data
  21.     {
  22.         cout << "X(X const& other) called" << endl;
  23.     }
  24.  
  25.     // Constructor3
  26.     X(X&& other):  // move constructor
  27.     data(std::move(other.data)) // move the data: no copies
  28.     {
  29.         cout << "X(X&& other) called" << endl;
  30.     }
  31.  
  32.     X& operator=(X const& other) // copy-assignment
  33.     {
  34.         cout << "X& operator=(X const& other) called" << endl;
  35.         data=other.data; // copy all the data
  36.         return *this;
  37.     }
  38.  
  39.     X& operator=(X && other) // move-assignment
  40.     {
  41.         cout << "X& operator=(X && other) called" << endl;
  42.         data=std::move(other.data); // move the data: no copies
  43.         return *this;
  44.     }
  45. };
  46.  
  47. class X2
  48. {
  49. public:
  50.  
  51.     std::vector<double> data;
  52.  
  53.     // Constructor1
  54.     X2()
  55.         : data(100000) // lots of data
  56.     {
  57.         cout << "X2() called" << endl;
  58.     }
  59.  
  60.     // Constructor2
  61.     X2(X const& other)
  62.         : data(other.data)
  63.     {
  64.         cout << "X2(const X&) called" << endl;
  65.     }
  66.  
  67.     X2& operator=(X const& other) // copy-assignment
  68.     {
  69.         data=other.data; // copy all the data
  70.         cout << "X2::operator =(const X&) called" << endl;
  71.         return *this;
  72.     }
  73. };
  74.  
  75. X make_x()
  76. {
  77.     X myNewObject; 
  78.     myNewObject.data.push_back(22);
  79.     return myNewObject;
  80. }
  81.  
  82.  
  83. int main()
  84. {
  85.     X x = make_x(); // x1 has a move constructor
  86.     X2 x2 = make_x(); // x2 hasn't a move constructor
  87.     return 0;
  88. }
Success #stdin #stdout 0s 2900KB
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X() called
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https://ideone.com/Gj2qee
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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