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  1. #include <iostream>
  2. #include <vector>
  3. #include <algorithm>
  4.  
  5. using namespace std;
  6.  
  7. template <
  8.     class InputIterator, class OutputIterator, 
  9.     class UnaryOperator, class Pred
  10. >
  11. OutputIterator transform_if(InputIterator first1, InputIterator last1,
  12.                             OutputIterator result, UnaryOperator op, Pred pred)
  13. {
  14.     while (first1 != last1) 
  15.     {
  16.         if (pred(*first1)) {
  17.             *result = op(*first1);
  18.             ++result;
  19.         }
  20.         ++first1;
  21.     }
  22.     return result;
  23. }
  24.  
  25. struct ha { 
  26. 	int i;
  27.     explicit ha(int a) : i(a) {}
  28. };
  29.  
  30. int main() 
  31. {
  32.     vector<ha> v{ ha{1}, ha{7}, ha{1} }; // initial vector
  33.     // GOAL : make a vector of pointers to elements with i < 2
  34.     vector<ha*> ph; // target vector
  35.  
  36.     // example call 
  37.     transform_if(v.begin(), v.end(), back_inserter(ph), 
  38.     [](ha &arg) { return &arg;      }, // 1. 
  39.     [](ha &arg) { return arg.i < 2; });// 2.
  40.  
  41.     return 0;
  42. }
  43.  
  44.  
Success #stdin #stdout 0s 3468KB
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Standard input is empty
stdout 
Standard output is empty
https://ideone.com/v77m3d
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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