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  1. #include <algorithm>
  2. #include <iostream>
  3.  
  4. class SIter {
  5.     public:
  6.  
  7.  
  8.        SIter(int* aIter, double* bIter) : aIter(aIter), bIter(bIter) {}
  9.  
  10.       // we move to next position is just moving both:
  11.       SIter& operator ++() {
  12.          ++aIter; ++bIter;
  13.          return *this;
  14.       }
  15.       SIter operator ++(int) {
  16.          SIter rv = *this;
  17.          ++aIter; ++bIter;
  18.          return rv;
  19.       }
  20.       SIter& operator --() {
  21.          --aIter; --bIter;
  22.          return *this;
  23.       }
  24.       SIter operator --(int) {
  25.          SIter rv = *this;
  26.          --aIter; --bIter;
  27.          return rv;
  28.       }
  29.       SIter operator + (std::ptrdiff_t cc) const
  30.       {
  31.           SIter rv = *this;
  32.           rv.aIter += cc;
  33.           rv.bIter += cc;
  34.           return rv;
  35.       }
  36.       SIter operator - (std::ptrdiff_t cc) const
  37.       {
  38.           SIter rv = *this;
  39.           rv.aIter -= cc;
  40.           rv.bIter -= cc;
  41.           return rv;
  42.       }
  43.       std::ptrdiff_t operator - (SIter other) const
  44.       {
  45.           return aIter - other.aIter;
  46.       }
  47.        struct value_type {
  48.           int a; double b;
  49.           bool operator < (const value_type& other) const {
  50.               return a < other.a; // this is the place where way of sorting is defined!!!!
  51.           }
  52.        };
  53.       struct reference {
  54.          int* a;
  55.          double* b;
  56.          reference& operator = (const value_type& o) 
  57.          {
  58.            *a = o.a;
  59.            *b = o.b;
  60.            return *this;
  61.          }
  62.          operator value_type() const {
  63.              value_type rv = { *a, *b };
  64.              return rv;
  65.          }
  66.          reference& operator = (const reference& other)
  67.          {
  68.             *a = *other.a;
  69.             *b = *other.b;
  70.             return *this;
  71.          }
  72.          bool operator < (const reference& other) const {
  73.             return *a < *other.a; 
  74.          }
  75.          bool operator < (const value_type& other) const {
  76.             return *a < other.a; 
  77.          }
  78.       };
  79.  
  80.       reference operator * () {
  81.          reference rv = { aIter, bIter };
  82.          return rv;
  83.       }
  84.       bool operator == (const SIter& other) const
  85.       {
  86.           return aIter == other.aIter; // don't need to compare bIter - shall be in sync
  87.       }
  88.       bool operator != (const SIter& other) const
  89.       {
  90.           return aIter != other.aIter; // don't need to compare bIter - shall be in sync
  91.       }
  92.       bool operator < (const SIter& other) const
  93.       {
  94.           return aIter < other.aIter; // don't need to compare bIter - shall be in sync
  95.       }
  96.       // I bet you don't need pointer operator -> ()
  97.        typedef std::random_access_iterator_tag iterator_category;
  98.        typedef std::ptrdiff_t difference_type;
  99.        typedef reference pointer;
  100.  
  101.  
  102.     private:
  103.       int* aIter; 
  104.       double* bIter;
  105.     };
  106.  
  107.  
  108.  
  109.  
  110.  
  111.     int main() {
  112.        int a[10] = {10,9,8,7,6,5,4,3,2,1};
  113.        double b[10] = {1,2,3,4,5,6,7,8,9,10};
  114.  
  115.        SIter beginIter(a, b);
  116.        SIter endIter(a + 10, b + 10);
  117.  
  118.        std::sort(beginIter, endIter);
  119.        for (int i = 0; i < 10; ++i) {
  120.            std::cout << a[i] << "->" << b[i] << "\n";
  121.        }
  122.     }
  123.  
  124.  
Success #stdin #stdout 0s 2900KB
comments ()
stdin 
Standard input is empty
stdout 
1->10
2->9
3->8
4->7
5->6
6->5
7->4
8->3
9->2
10->1
https://ideone.com/rbC8Vd
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
secret

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