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  1. #include <iostream>
  2. #include <vector>
  3.  
  4. class VisualizableVector {
  5.   public:
  6.     class proxy {
  7.       public:
  8.         proxy (std::vector<int> *v) : vect (v) {
  9.         	std::cout << "Before size is: " << vect->size() << std::endl;
  10.         }
  11.         std::vector<int> * operator -> () { return vect; }
  12.         std::vector<int> & operator * () { return *vect; }
  13.         ~proxy () { std::cout << "After size is: " << vect->size() << std::endl; }
  14.       private:
  15.         std::vector <int> * vect;
  16.     };
  17.  
  18.     VisualizableVector (std::vector<int> *v) : vect(v) {}    
  19.     ~VisualizableVector () { delete vect; }
  20.     proxy operator -> () { return proxy (vect); }
  21.     proxy operator * () { return proxy (vect); }
  22.   private:
  23.     std::vector <int> * vect;
  24. };
  25.  
  26. int main()
  27. {
  28.   VisualizableVector vecc (new std::vector<int>);
  29.  
  30.   vecc->push_back (10); 	// 1. Note use of -> operator instead of . operator
  31.   vecc->push_back (20); 	// 2. ok
  32.   (*vecc)->push_back (30);	// 3. ok
  33.   //(*vecc).push_back (40);	// 4. error
  34.   (**vecc).push_back (50);	// 5. ok
  35.   //vecc->->push_back (60);	// 6. error
  36. }
Success #stdin #stdout 0s 3464KB
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stdin
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Standard input is empty
stdout
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Before size is: 0
After size is: 1
Before size is: 1
After size is: 2
Before size is: 2
After size is: 3
Before size is: 3
After size is: 4
https://ideone.com/cXGdxW
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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