Sample C++/STL custom iterator

custom_iterator.cpp

// Sample custom iterator.
// By perfectly.insane (http://www.dreamincode.net/forums/index.php?showuser=76558)
// From: http://www.dreamincode.net/forums/index.php?showtopic=58468

#include <iostream>
#include <vector>
#include <algorithm>
#include <iterator>
#include <cassert>

template <typename T>
class fixed_array
{
    public:

        typedef int size_type;

        class iterator
        {
            public:
                typedef iterator self_type;
                typedef T value_type;
                typedef T& reference;
                typedef T* pointer;
                typedef std::forward_iterator_tag iterator_category;
                typedef int difference_type;
                iterator(pointer ptr) : ptr_(ptr) { }
                self_type operator++() { self_type i = *this; ptr_++; return i; }
                self_type operator++(int junk) { ptr_++; return *this; }
                reference operator*() { return *ptr_; }
                pointer operator->() { return ptr_; }
                bool operator==(const self_type& rhs) { return ptr_ == rhs.ptr_; }
                bool operator!=(const self_type& rhs) { return ptr_ != rhs.ptr_; }
            private:
                pointer ptr_;
        };

        class const_iterator
        {
            public:
                typedef const_iterator self_type;
                typedef T value_type;
                typedef T& reference;
                typedef T* pointer;
                typedef int difference_type;
                typedef std::forward_iterator_tag iterator_category;
                const_iterator(pointer ptr) : ptr_(ptr) { }
                self_type operator++() { self_type i = *this; ptr_++; return i; }
                self_type operator++(int junk) { ptr_++; return *this; }
                const reference operator*() { return *ptr_; }
                const pointer operator->() { return ptr_; }
                bool operator==(const self_type& rhs) { return ptr_ == rhs.ptr_; }
                bool operator!=(const self_type& rhs) { return ptr_ != rhs.ptr_; }
            private:
                pointer ptr_;
        };


        fixed_array(size_type size) : size_(size) {
            data_ = new T[size_];
        }

        size_type size() const { return size_; }

        T& operator[](size_type index)
        {
            assert(index < size_);
            return data_[index];
        }

        const T& operator[](size_type index) const
        {
            assert(index < size_);
            return data_[index];
        }

        iterator begin()
        {
            return iterator(data_);
        }

        iterator end()
        {
            return iterator(data_ + size_);
        }

        const_iterator begin() const
        {
            return const_iterator(data_);
        }

        const_iterator end() const
        {
            return const_iterator(data_ + size_);
        }

    private:
        T* data_;
        size_type size_;
};


int main()
{
    fixed_array<double> point3d(3);
    point3d[0] = 2.3;
    point3d[1] = 3.2;
    point3d[2] = 4.2;

    for(fixed_array<double>::iterator i = point3d.begin(); i != point3d.end(); i++)
    {
        std::cout << *i << " ";
    }

    std::cout << std::endl;

    std::vector<double> vec;
    std::copy(point3d.begin(), point3d.end(), std::back_inserter(vec));

    for(std::vector<double>::iterator i = vec.begin(); i != vec.end(); i++)
    {
        std::cout << *i << " ";
    }

    std::cout << std::endl;
    return 0;
}