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  1. #include <iostream>
  2. #include <string>
  3.  
  4. class T
  5. {
  6. public:
  7. 	T(const std::string& name): name_(name), copy_(0), move_(0){}
  8. 	T(const T& rhs)
  9. 		: name_(rhs.name_), copy_(rhs.copy_), move_(rhs.move_)
  10. 	{
  11. 		copy_++;
  12. 	}
  13. 	T(T&& rhs)
  14. 		: name_(rhs.name_), copy_(rhs.copy_), move_(rhs.move_)
  15. 	{
  16. 		swap(rhs);
  17. 		move_++;
  18. 	}
  19.  
  20. 	void swap(T& rhs)
  21. 	{
  22. 		std::swap(name_, rhs.name_);
  23. 		std::swap(copy_, rhs.copy_);
  24. 		std::swap(move_, rhs.move_);
  25. 	}
  26.  
  27. 	void op()
  28. 	{ 
  29. 		std::cout << name_ << "-copy: " << copy_ 
  30. 			<< ", move: " << move_ << std::endl; 
  31. 	}
  32. private:
  33. 	int copy_;
  34. 	int move_;
  35. 	std::string name_;
  36. };
  37.  
  38. T op1(const T& val) // pass by const reference
  39. {
  40. 	std::cout << "op1" << std::endl;
  41. 	T tmp(val);	//copy ctor
  42. 	tmp.op();
  43. 	return tmp;
  44. }
  45.  
  46. T op2(T val) // pass by value
  47. {
  48. 	std::cout << "op2" << std::endl;
  49. 	val.op();
  50. 	return val;
  51. }
  52.  
  53. T op3(T&& val) // pass by rvalue reference
  54. {
  55. 	std::cout << "op3" << std::endl;
  56. 	val.op();
  57. 	return val;
  58. }
  59.  
  60. T op4(const T& val) // pass by const lvalue reference
  61. {
  62. 	std::cout << "op4 [A]" << std::endl;
  63. 	T tmp(val);
  64. 	tmp.op();
  65. 	return tmp;
  66. }
  67. T op4(T&& val) // pass by rvalue reference
  68. {
  69. 	std::cout << "op4 [B]" << std::endl;
  70. 	val.op();
  71. 	return val;
  72. }
  73.  
  74. T op5(const T& val) // pass by const lvalue reference
  75. {
  76. 	std::cout << "op5 [A]" << std::endl;
  77. 	T tmp(val);
  78. 	tmp.op();
  79. 	return tmp;
  80. }
  81. T op5(T&& val) // pass by rvalue reference
  82. {
  83. 	std::cout << "op5 [B]" << std::endl;
  84. 	val.op();
  85. 	return std::move(val);
  86. }
  87.  
  88.  
  89. int main( int argc, char* argv[] )
  90. {
  91. 	T t("lvalue");	
  92.  
  93. 	op1(t).op();
  94. 	T t1("xvalue");	
  95. 	op1(std::move(t1)).op();
  96. 	op1(T("rvalue")).op();
  97.  
  98. 	op2(t).op();
  99. 	T t2("xvalue");	
  100. 	op2(std::move(t2)).op();
  101. 	op2(T("rvalue")).op();
  102.  
  103. 	//op3(t).op();	//error
  104. 	T t3("xvalue");	
  105. 	op3(std::move(t3)).op();
  106. 	op3(T("rvalue")).op();
  107.  
  108. 	op4(t).op();
  109. 	T t4("xvalue");	
  110. 	op4(std::move(t4)).op();
  111. 	op4(T("rvalue")).op();
  112.  
  113. 	op5(t).op();
  114. 	T t5("xvalue");	
  115. 	op5(std::move(t5)).op();
  116. 	op5(T("rvalue")).op();
  117.  
  118. 	return 0;
  119. }
Success #stdin #stdout 0s 3072KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
op1
lvalue-copy: 1, move: 0
lvalue-copy: 1, move: 0
op1
xvalue-copy: 1, move: 0
xvalue-copy: 1, move: 0
op1
rvalue-copy: 1, move: 0
rvalue-copy: 1, move: 0
op2
lvalue-copy: 1, move: 0
lvalue-copy: 2, move: 0
op2
xvalue-copy: 0, move: 1
xvalue-copy: 1, move: 1
op2
rvalue-copy: 0, move: 0
rvalue-copy: 1, move: 0
op3
xvalue-copy: 0, move: 0
xvalue-copy: 1, move: 0
op3
rvalue-copy: 0, move: 0
rvalue-copy: 1, move: 0
op4 [A]
lvalue-copy: 1, move: 0
lvalue-copy: 1, move: 0
op4 [B]
xvalue-copy: 0, move: 0
xvalue-copy: 1, move: 0
op4 [B]
rvalue-copy: 0, move: 0
rvalue-copy: 1, move: 0
op5 [A]
lvalue-copy: 1, move: 0
lvalue-copy: 1, move: 0
op5 [B]
xvalue-copy: 0, move: 0
xvalue-copy: 0, move: 1
op5 [B]
rvalue-copy: 0, move: 0
rvalue-copy: 0, move: 1
https://ideone.com/wcGsR
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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