A small program to reverse the order of words in a string

reverse.cpp

#include <string>
#include <iostream>
#include <algorithm>

using namespace std;

/*
 *
 * Small program to reverse the order of words in a sentence
 *
 * */

string * reverseSentence(const string & input){

   // This will be the return value
   //
   // We resize it to the exact same length as the input.
   // We're not changing the characters in the string, only
   // their order
   string * output = new string;
   output->resize(input.length());

   // Iterators to the input string.
   //
   // i_it   -- This is the iterator that is going to be constantly
   //           moving along the input string
   //
   // i_w_it -- This iterator is going to be set to the beginning of
   //           words as they are found
   //           
   // i_end  -- This is just checked against so we don't go past the end
   string::const_iterator i_it = input.begin();
   string::const_iterator i_w_it = input.begin();
   string::const_iterator i_end= input.end();

   // Iterator to the end of the output string. This is going to walk
   // backwards down the output as the input iterator walks up the input
   // string. This iterator will always be the position in the output
   // where the next word should be copied to
   string::iterator o_it = output->end();

   while(i_it != i_end){
      // Skip to the end of the current word, decrementing the output
      // while simultaneously decrementing the output iterator the right
      // amount of positions
      while(i_it != i_end && *i_it != ' ') ++i_it, --o_it;

      // The state of the iterators should now be:
      //
      // i_it   = right after the end of the current word
      //
      // i_w_it = the beginning of the current word
      //
      // o_it   = the position in the output where the next
      //          word should be inserted.
      //
      //
      // At this point we use the three iterators described above to
      // copy the current word into the output.
      copy(i_w_it, i_it, o_it);

      // if we're not at the end of the input, then we insert a space
      // into the output and update i_w_it, 
      if(i_it != i_end){
         *(--o_it) = ' ';
         ++i_it;
         i_w_it = i_it;
      }

      // that's all, folks
   }

   return output;
}

int main(int argc, const char *argv[])
{
   // Get input
   char buff[1024];

   cout << "Enter the string to be reversed" << endl << ">>> ";

   cin.getline(buff, 1024, '\n');
   string input(buff);

   // Produce and print output
   string * output = reverseSentence(input);

   cout << "input : \"" << input   << '"' << endl
        << "output: \"" << *output << '"' << endl;

   delete output;
   
   return 0;
}