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  1. #include <iostream>
  2. #include <vector>
  3. #include <algorithm>
  4. #include <iterator>
  5.  
  6. template <typename iter_type>
  7. void print(iter_type beg, iter_type end)
  8. {
  9.     std::cout << "{ ";
  10.     while (beg != end)
  11.         std::cout << *beg++ << ' ';
  12.     std::cout << "}\n";
  13. }
  14.  
  15. template <typename container_type>
  16. void print(const container_type& container)
  17. {
  18.     print(std::begin(container), std::end(container));
  19. }
  20.  
  21. void remove_copies_of_front_with_remove_erase_idiom(std::vector<int>& v)
  22. {
  23.     v.erase(std::remove(v.begin()+1, v.end(), v.front()), v.end());
  24. }
  25.  
  26. void remove_copies_of_front_with_while_loop(std::vector<int>& v)
  27. {
  28.     unsigned i = 1;
  29.     while (i < v.size())
  30.     {
  31.         if (v[i] == v[0])
  32.             v.erase(v.begin() + i);
  33.         else
  34.             ++i;
  35.     }
  36. }
  37.  
  38. int main()
  39. {
  40.     using vec_t = std::vector<int>;
  41.  
  42.     vec_t original = { 1, 1, 1, 2, 1, 3, 1, 1, 4, 1, 1, 5 };
  43.     vec_t expected_result = { 1, 2, 3, 4, 5 };
  44.  
  45.     auto a = original;
  46.     std::cout << "Before remove-erase idiom applied\n\ta: ";
  47.     print(a);
  48.  
  49.     remove_copies_of_front_with_remove_erase_idiom(a);
  50.     std::cout << "\nAfter removal\n\ta: ";
  51.     print(a);
  52.  
  53.     if (a == expected_result)
  54.         std::cout << "Success!\n\n";
  55.     else
  56.         std::cout << "Failure!\n\n";
  57.  
  58.     auto b = original;
  59.     std::cout << "Before while removal\n\tb: ";
  60.     print(b);
  61.  
  62.     remove_copies_of_front_with_while_loop(b);
  63.     std::cout << "\nAfter removal\n\tb: ";
  64.     print(b);
  65.  
  66.     if (b == expected_result)
  67.         std::cout << "Success!\n\n";
  68.     else
  69.         std::cout << "Failure!\n\n";
  70. }
Success #stdin #stdout 0s 3432KB
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stdin
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Standard input is empty
stdout
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Before remove-erase idiom applied
	a: { 1 1 1 2 1 3 1 1 4 1 1 5 }

After removal
	a: { 1 2 3 4 5 }
Success!

Before while removal
	b: { 1 1 1 2 1 3 1 1 4 1 1 5 }

After removal
	b: { 1 2 3 4 5 }
Success!
https://ideone.com/JalrWr
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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