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  1. #include <iostream>
  2. #include <string>
  3. #include <cstring> //std::memcpy
  4.  
  5. class CustomClass
  6. {
  7. private:
  8. 	std::string a;
  9. 	std::string b;
  10. public:
  11. 	CustomClass(std::string a, std::string b): a(a), b(b) {}
  12. 	std::string to_string()
  13. 	{
  14. 		return a + " of " + b;
  15. 	}
  16. };
  17.  
  18. class CustomArray
  19. {
  20. private:
  21.  
  22. 	CustomClass **arr = nullptr;
  23. 	size_t capacity = 0;
  24. 	size_t size = 0;
  25.  
  26.  
  27. public:
  28.  
  29. 	void resize(size_t new_capacity) 
  30. 	{
  31. 		CustomClass** resized_arr = new CustomClass*[new_capacity]();
  32. 		std::memcpy(resized_arr, arr, capacity * sizeof(CustomClass*));
  33.  
  34. 		delete[] arr;
  35.  
  36. 		capacity = new_capacity;
  37. 		arr = resized_arr;
  38.  
  39. 	}
  40. 	void add(CustomClass* cc)
  41. 	{
  42. 		if (size <= capacity)
  43. 			this->resize(capacity + 1);
  44.  
  45. 		arr[size++] = cc;
  46. 	}
  47.  
  48. 	void print() 
  49. 	{
  50. 		for (size_t i = 0; i < capacity; i++) 
  51. 		{
  52. 			if (arr[i] == nullptr) 
  53. 				std::cout << "KEY: " << i << ", VAL: NULL" << std::endl;
  54. 			else
  55. 				std::cout << "KEY: " << i << ", VAL: " << arr[i]->to_string() << std::endl;
  56. 		}
  57.  
  58. 		std::cout << std::endl;
  59. 	}
  60. };
  61.  
  62.  
  63.  
  64. int main()
  65. {
  66. 	CustomArray arr;
  67. 	arr.print(); // nothing
  68.  
  69. 	CustomClass cc1("1", "3");
  70. 	arr.add(&cc1);
  71. 	CustomClass cc2("2", "3");
  72. 	arr.add(&cc2);
  73. 	CustomClass cc3("3", "3");
  74. 	arr.add(&cc3);
  75. 	arr.print(); // prints 3 elements
  76.  
  77. 	arr.resize(5);
  78. 	arr.print(); //prints 2 nore NULLs
  79.  
  80.  
  81. 	return 0;
  82. }
Success #stdin #stdout 0s 16064KB
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stdin
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Standard input is empty
stdout
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KEY: 0, VAL: 1 of 3
KEY: 1, VAL: 2 of 3
KEY: 2, VAL: 3 of 3

KEY: 0, VAL: 1 of 3
KEY: 1, VAL: 2 of 3
KEY: 2, VAL: 3 of 3
KEY: 3, VAL: NULL
KEY: 4, VAL: NULL
https://ideone.com/HStRBI
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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