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  1. #include <iostream>
  2. #include <cassert>
  3.  
  4. // The Official proposal
  5. // http://w...content-available-to-author-only...d.org/jtc1/sc22/wg21/docs/papers/2007/n2431.pdf
  6. const // this is a const object... 
  7. class {
  8. public:
  9. 	template<class T> // convertible to any type 
  10. 	operator T*() const // of null non-member 
  11. 	{
  12. 		return 0;
  13. 	} // pointer... 
  14.  
  15. 	template<class C, class T> // or any type of null 
  16. 	operator T C::*() const // member pointer... 
  17. 	{
  18. 		return 0;
  19. 	}
  20.  
  21. private:
  22. 	void operator&() const; // whose address can't be taken 
  23. } my_nullptr = {}; // and whose name is nullptr
  24.  
  25.  
  26. struct Test123 {
  27. 	int ABCD, ABC, AB;
  28. 	int A;
  29. 	int BA, CBA, DCBA;
  30. 	struct XYZ {
  31. 		char X, Y, Z, W;
  32. 	};
  33. 	struct {
  34. 		int B, C, D;
  35. 	};
  36. } test123;
  37.  
  38.  
  39. class Test {
  40. 	int ABCD;
  41. public:
  42. 	void method(void){}
  43.  
  44. 	Test(int val) :ABCD(val){}
  45. 	int getABCD(void) const { return ABCD; }
  46. 	int get2ABCD(void) const { return ABCD * 2; }
  47. 	int get3ABCD(void) const { return ABCD * 3; }
  48. } test(0123);
  49.  
  50.  
  51. int main(int argc, char* argv[])
  52. {
  53.  
  54. 	// TEST_my_nullptr
  55. 	{
  56. 		int a = 321, *p = my_nullptr;
  57. 		assert(p == my_nullptr);
  58. 		assert(my_nullptr == p);
  59.  
  60. 		p = &a; *p = 0123;
  61. 		assert(p != my_nullptr);
  62. 		assert(my_nullptr != p);
  63.  
  64. 		p = my_nullptr;
  65.  
  66. 		int(*mainptr)(int argc, char** argv) = my_nullptr;
  67. 		assert(mainptr == my_nullptr);
  68. 		assert(my_nullptr == mainptr);
  69. 	}
  70.  
  71.  
  72. 	// TEST_my_nullptr_const
  73. 	{
  74. 		const int a = 321, *p = my_nullptr;
  75. 		assert(p == my_nullptr);
  76. 		assert(my_nullptr == p);
  77.  
  78. 		p = &a;
  79. 		assert(p != my_nullptr);
  80. 		assert(my_nullptr != p);
  81.  
  82. 		const int** ptr = my_nullptr;
  83.  
  84. 		assert(ptr == my_nullptr);
  85. 		assert(my_nullptr == ptr);
  86.  
  87. 		ptr = &p;
  88. 		assert(ptr != my_nullptr);
  89. 		assert(my_nullptr != ptr);
  90. 		assert(*ptr != my_nullptr);
  91. 		assert(my_nullptr != *ptr);
  92.  
  93. 	}
  94.  
  95.  
  96. 	// TEST_my_nullptr_member
  97. 	{
  98. 		int Test123::*pINT = my_nullptr;
  99. 		assert(pINT == my_nullptr);
  100. 		assert(my_nullptr == pINT);
  101.  
  102. 		pINT = &Test123::ABCD;
  103. 		assert(pINT != my_nullptr);
  104. 		assert(my_nullptr != pINT);
  105.  
  106. 		test123.*pINT = 0123;
  107.  
  108. 		const int Test123::*pCINT = my_nullptr;
  109. 		assert(pCINT == my_nullptr);
  110. 		assert(my_nullptr == pCINT);
  111.  
  112. 		pCINT = &Test123::ABCD;
  113. 		assert(pCINT != my_nullptr);
  114. 		assert(my_nullptr != pCINT);
  115.  
  116. 		assert(test123.*pCINT == test123.*pINT);
  117. 	}
  118.  
  119. 	// TEST_my_nullptr_Function
  120. {
  121. 	void (Test::*pm)(void) = my_nullptr;
  122.  
  123. 	pm = &Test::method;
  124.  
  125. 	int (Test::*pABCD)(void) const = my_nullptr; // This F**k Line In VS2013
  126.  
  127. 	pABCD = &Test::getABCD;
  128.  
  129. 	int a1 = (test.*pABCD)();
  130.  
  131. 	pABCD = &Test::get2ABCD;
  132. 	int a2 = (test.*pABCD)();
  133.  
  134. 	pABCD = &Test::get3ABCD;
  135. 	int a3 = (test.*pABCD)();
  136.  
  137. 	assert(a1 + a2 == a3);
  138. }
  139.  
  140. 	std::cout << "All Tests for my_nullptr Passed!" << std::endl;
  141. 	return 0;
  142. }
  143.  
Success #stdin #stdout 0s 2684KB
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Standard input is empty
stdout
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All Tests for my_nullptr Passed!
https://ideone.com/aX1OZ8
language:
C++ 4.3.2 (gcc-4.3.2)
created:
10 years ago
visibility:
public

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