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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. class A
  5. {
  6. public:
  7. 	virtual ~A()
  8. 	{
  9. 		cout << "~A()" << endl;
  10. 	}
  11.  
  12. 	void* operator new (std::size_t size)
  13. 	{
  14. 		cout << "void* operator new (std::size_t size)" << endl;
  15. 		return ::operator new(size);
  16. 	}
  17.  
  18. 	// placement new
  19. 	void* operator new (std::size_t size, void* ptr) noexcept
  20. 	{
  21. 		cout << "void* operator new (std::size_t size, void* ptr) noexcept" << endl;
  22. 		return ::operator new(size, ptr);
  23. 	}
  24.  
  25. 	void operator delete (void* ptr, std::size_t size) noexcept
  26. 	{
  27. 		// От куда компиль взял размер класса B?
  28. 		cout << "delete (void* ptr, std::size_t size); size = " << size << "!!!" << endl;
  29. 		::operator delete(ptr);
  30. 	}
  31.  
  32. 	void operator delete (void* ptr, void* voidptr2) noexcept
  33. 	{
  34. 		cout << "void operator delete (void* ptr, void* voidptr2) noexcept" << endl;
  35. 		::operator delete(ptr, voidptr2);	
  36. 	}
  37.  
  38. 	void* operator new (std::size_t size, const std::nothrow_t& nothrow_value) noexcept = delete;
  39. 	void* operator new[] (std::size_t size) = delete;
  40. 	void* operator new[] (std::size_t size, const std::nothrow_t& nothrow_value) noexcept = delete;
  41. 	void* operator new[] (std::size_t size, void* ptr) noexcept = delete;
  42.  
  43. 	void operator delete (void* ptr, const std::nothrow_t& nothrow_constant) noexcept = delete;
  44. 	void operator delete[] (void* ptr) noexcept = delete;
  45. 	void operator delete[] (void* ptr, const std::nothrow_t& nothrow_constant) noexcept;
  46. 	void operator delete[] (void* ptr, void* voidptr2) noexcept = delete;
  47.  
  48. private:
  49. 	int _i1;
  50. };
  51.  
  52. class B : public A
  53. {
  54. public:
  55. 	virtual ~B()
  56. 	{
  57. 		cout << "~B()" << endl;
  58. 	}
  59.  
  60. private:
  61. 	int _i2;
  62. 	int _i3;
  63. };
  64.  
  65. int main() {
  66. 	cout << "sizeof(A) = " << sizeof(A) << endl;
  67. 	cout << "sizeof(B) = " << sizeof(B) << endl << endl;
  68.  
  69. 	B* b = new B();
  70. 	delete (A*)b; // call sized deallocation function
  71.  
  72. 	B* b2 = reinterpret_cast<B*>(::operator new(sizeof(B)));
  73. 	new(b2) B(); 
  74. 	delete (A*)b2; // call sized deallocation function
  75.  
  76. 	return 0;
  77. }
  78.  
Success #stdin #stdout 0s 15240KB
comments (?)
stdin 
Standard input is empty
stdout 
sizeof(A) = 16
sizeof(B) = 24

void* operator new (std::size_t size)
~B()
~A()
delete (void* ptr, std::size_t size); size = 24!!!
void* operator new (std::size_t size, void* ptr) noexcept
~B()
~A()
delete (void* ptr, std::size_t size); size = 24!!!
https://ideone.com/wPFFwo
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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