counting unique

counting_unique.cpp

#include <cstdlib>
namespace pwned {

template <class ForwardIterator, class OutputIterator>
  ForwardIterator counting_unique (ForwardIterator first, ForwardIterator last, OutputIterator out)
{
  if (first==last) return last;

  ForwardIterator result = first;
  std::size_t count= 1;
  while (++first != last)
  {
    if (!(*result == *first))
    {
      *(++result)=*first;
      *out= count;
      ++ out;
      count= 1;
    }
    else
    {
      ++ count;
    }
  }

  *out= count;
  ++ out;
  return ++result;
}
} // pwned

#include <iostream>
#include <iterator>

int main()
{
  int a[]= { 1, 1, 2, 3, 3, 4, 4, 5, 4, 4, 4 };
  std::ostream_iterator<int> out(std::cout);
  int* e= pwned::counting_unique(a, a+ 11, out);
  std::cout<< std::endl;
  std::copy(a, e, out);
}