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  1. #include <iostream>
  2. #include <vector>
  3. #include <memory>
  4. using namespace std;
  5.  
  6. class IA
  7. {
  8. public:
  9. 	virtual ~IA() {}
  10. 	void A() { cout << "A" << endl; }
  11. };
  12. class IB
  13. {
  14. public:
  15. 	virtual ~IB() {}
  16. 	void B() { cout << "A" << endl; }
  17. };
  18. class IC
  19. {
  20. public:
  21. 	virtual ~IC() {}
  22. 	void C() { cout << "A" << endl; }
  23. };
  24.  
  25. class C : IA, IB, IC
  26. {
  27. public:
  28. };
  29.  
  30. void QueryInterface(int n, C* cthis, void** ptr)
  31. {
  32. 	switch (n)
  33. 	{
  34. 	case 1:
  35. 		*ptr = reinterpret_cast<IA*>(cthis);
  36. 		break;
  37. 	case 2:
  38. 		*ptr = reinterpret_cast<IB*>(cthis);
  39. 		break;
  40. 	case 3:
  41. 		*ptr = reinterpret_cast<IC*>(cthis);
  42. 		break;
  43. 	}
  44. }
  45.  
  46. void QueryInterface2(int n, C* cthis, void** ptr)
  47. {
  48. 	switch (n)
  49. 	{
  50. 	case 1:
  51. 		*ptr = (IA*)cthis;
  52. 		break;
  53. 	case 2:
  54. 		*ptr = (IB*)cthis;
  55. 		break;
  56. 	case 3:
  57. 		*ptr = (IC*)cthis;
  58. 		break;
  59. 	}
  60. }
  61. int main() {
  62. 	IA* ptr;
  63. 	cout<<"Cpp style cast."<<endl;
  64. 	C c;
  65. 	QueryInterface(1, &c, (void**)&ptr);
  66. 	cout << ptr << endl;
  67. 	QueryInterface(2, &c, (void**)&ptr);
  68. 	cout << ptr << endl;
  69. 	QueryInterface(3, &c, (void**)&ptr);
  70. 	cout << ptr << endl;
  71.  
  72. 	cout<<"C style cast."<<endl;
  73. 	QueryInterface2(1, &c, (void**)&ptr);
  74. 	cout << ptr << endl;
  75. 	QueryInterface2(2, &c, (void**)&ptr);
  76. 	cout << ptr << endl;
  77. 	QueryInterface2(3, &c, (void**)&ptr);
  78. 	cout << ptr << endl;
  79.  
  80. 	return 0;
  81. }
Success #stdin #stdout 0s 4400KB
comments (?)
stdin 
Standard input is empty
stdout 
Cpp style cast.
0x7ffc457df220
0x7ffc457df220
0x7ffc457df220
C style cast.
0x7ffc457df220
0x7ffc457df228
0x7ffc457df230
https://ideone.com/fYoRWE
language:
C++ (gcc 8.3)
created:
4 years ago
visibility:
public

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