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## Class template counting_iterator

boost::compute::counting_iterator — The counting_iterator class implements a counting iterator.

## Synopsis

    // In header: <boost/compute/iterator/counting_iterator.hpp>

    template<typename T>
    class counting_iterator {
    public:
      // types
      typedef unspecified                 super_type;
      typedef super_type::reference       reference;
      typedef super_type::difference_type difference_type;

      // construct/copy/destruct
      counting_iterator(const T &);
      counting_iterator(const counting_iterator< T > &);
      counting_iterator< T > & operator=(const counting_iterator< T > &);
      ~counting_iterator();

      // public member functions
      size_t get_index() const;
      template<typename Expr> unspecified operator[](const Expr &) const;

      // private member functions
      reference dereference() const;
      bool equal(const counting_iterator< T > &) const;
      void increment();
      void decrement();
      void advance(difference_type);
      difference_type distance_to(const counting_iterator< T > &) const;
    };

## Description

A counting iterator returns an internal value (initialized with `init`) which is incremented each time the iterator is incremented.

For example, this could be used to implement the iota() algorithm in terms of the copy() algorithm by copying from a range of counting iterators:

See Also:

make_counting_iterator()

### `counting_iterator` public construct/copy/destruct

1.     counting_iterator(const T & init);

2.     counting_iterator(const counting_iterator< T > & other);

3.     counting_iterator< T > & operator=(const counting_iterator< T > & other);

4.     ~counting_iterator();

### `counting_iterator` public member functions

1.     size_t get_index() const;

2.     template<typename Expr> unspecified operator[](const Expr & expr) const;

### `counting_iterator` private member functions

1.     reference dereference() const;

2.     bool equal(const counting_iterator< T > & other) const;

3.     void increment();

4.     void decrement();

5.     void advance(difference_type n);

6.     difference_type distance_to(const counting_iterator< T > & other) const;