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  1. #include <cstdio>    	// for printf, getchar.
  2. using namespace std;
  3.  
  4. int g_count;
  5.  
  6. struct my_string
  7. {
  8. 	int id;
  9.  
  10. 	my_string()
  11. 	{
  12. 		this->id = ++g_count;
  13. 		printf("my_string() / [id=%d]を生成\n", this->id);
  14. 	}
  15.  
  16. 	~my_string()
  17. 	{
  18. 		if ( this->id > 0 )
  19. 			printf("~my_string() / [id=%d]を破棄\n", this->id);
  20. 		else
  21. 			printf("~my_string() / 解放リソース無し\n");
  22. 	}
  23.  
  24. 	my_string(my_string const &other)
  25. 	{
  26. 		this->id = ++g_count;
  27. 		printf("my_string(my_string const &) / 生成[%d ← %d]\n",
  28. 			this->id, other.id);
  29. 	}
  30.  
  31. 	my_string(my_string &&other)
  32. 	{
  33. 		this->id = other.id;
  34. 		other.id = -1;
  35. 		printf("my_string(my_string &&) / [id=%d]を引き継ぎ\n", this->id);
  36. 	}
  37.  
  38. 	void operator=(my_string const &other)
  39. 	{
  40. 		printf("operator=(my_string const &) / [id=%d]を破棄\n", this->id);
  41. 		this->id = ++g_count;
  42. 		printf("operator=(my_string const &) / 生成[%d ← %d]\n",
  43. 			this->id, other.id);
  44. 	}
  45.  
  46. 	void operator=(my_string &&other)
  47. 	{
  48. 		printf("operator=(my_string &&) / [id=%d]を破棄\n", this->id);
  49. 		this->id = other.id;
  50. 		other.id = -1;
  51. 		printf("operator=(my_string &&) / [%d]を引き継ぎ\n", this->id);
  52. 	}
  53. };
  54.  
  55. my_string f()
  56. {
  57. 	return my_string();
  58. }
  59.  
  60. void f2(my_string &r)
  61. {
  62. 	r = my_string();
  63. }
  64.  
  65.  
  66. int main()
  67. {
  68. 	my_string i;
  69.  
  70. 	printf("\n----f\n");
  71. 	i = f(), printf(" (after return)\n");
  72.  
  73. 	printf("\n----f2\n");
  74. 	f2(i), printf(" (after return)\n");
  75. 	printf("\n----\n");
  76. }
  77.  
  78.  
Success #stdin #stdout 0s 2896KB
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stdin
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Standard input is empty
stdout
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my_string() / [id=1]を生成

----f
my_string() / [id=2]を生成
operator=(my_string &&) / [id=1]を破棄
operator=(my_string &&) / [2]を引き継ぎ
 (after return)
~my_string() / 解放リソース無し

----f2
my_string() / [id=3]を生成
operator=(my_string &&) / [id=2]を破棄
operator=(my_string &&) / [3]を引き継ぎ
~my_string() / 解放リソース無し
 (after return)

----
~my_string() / [id=3]を破棄
https://ideone.com/pEMjxW
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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