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  1. #include <iostream>
  2. #include <vector>
  3.  
  4. class Vec {
  5.   std::vector<double> mData;
  6.   int mSize;
  7. public:
  8.   Vec(int size) : mData(std::vector<double>(size,0)), mSize(size) { 
  9.       std::cout << "constructed" << std::endl;
  10.   }
  11.   double& operator[](int i) {return mData[i];}
  12.   double operator[](int i) const {return mData[i];}
  13.   Vec choose(const Vec& ifPositive, const Vec& ifNegative) const;
  14.   Vec& setNegative(Vec& target, const Vec& ifNegative) const;
  15. };
  16.  
  17. Vec Vec::choose(const Vec& ifPositive, const Vec& ifNegative) const {
  18.     Vec out(mSize);
  19.     for(int index = 0; index < mSize; ++index) {
  20.         if(mData[index] > 0)
  21.             out[index] = ifPositive[index];
  22.         else
  23.             out[index] = ifNegative[index];
  24.     }
  25.     return out;
  26. }
  27.  
  28. Vec& Vec::setNegative(Vec& target, const Vec& ifNegative) const {
  29.     for(int index = 0; index < mSize; ++index) {
  30.         if(mData[index] <= 0)
  31.             target[index] = ifNegative[index];
  32.     }
  33.     return target;
  34. }
  35.  
  36. int main() {
  37.     const int size = 100;
  38.  
  39.     Vec trigger(size); // 1. constructor
  40.     for(int i = 0; i < size; ++i) {
  41.         if(i < size/2)
  42.             trigger[i] = -1;
  43.         else
  44.             trigger[i] = 1;
  45.     }
  46.  
  47.     Vec valA(size), valB(size); // 2. & 3. constructor
  48.     for(int i = 0; i < size; ++i) {
  49.         valA[i] = 1;
  50.         valB[i] = 2;
  51.     }
  52.  
  53.     valA = trigger.choose(valA, valB); // 4. constructor -> not necessary, see next line
  54.     valA = trigger.setNegative(valA, valB); // no constructor
  55.  
  56.     Vec valC = trigger.choose(valA, valB); // 5. constructor -> okay
  57.  
  58. }
Success #stdin #stdout 0s 2988KB
comments (?)
stdin 
Standard input is empty
stdout 
constructed
constructed
constructed
constructed
constructed
https://ideone.com/nPUK3h
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
public

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