//------------------------------------------------
// File: MaxString1.cpp
//
// Author: D. Frey
// Date  : 8/21/03
// Section: 1234
// Project: none
// Description
//   This program is an example of using C++ string
// objects.  It includes string input (using the
// >> extraction operator) and output,
// string comparisons, strings as parameters and
// function return values and manipulating indvidual characters
// within a string
//--------------------------------------------------
//  This program reads strings from the user until
// the user types "quit".  It then prints the longest
// string seen forwards and backwards
//---------------------------------------------------
#include <iostream>
#include <string>

using namespace std;

// prototypes for functions in this file
string Reverse( string s);

// constants in this file
const string QUIT = "quit";


int main ( )
{
   string input;
   string longestString;

   // "priming read" for the while loop
   cout << "Please input a string:";
   cin >> input;

   while (input != QUIT)
   {
      // check if the new string is longer than
      // longest seen so far
      if (input.size() > longestString.size())
	 longestString = input;

      // get the next string from the user
      cout << "Please input a string:";
      cin >> input;
      
   }

   // reverse the string
   string backwards = Reverse( longestString );

   // output string forwards and backwards
   cout << "\nThe longest string has " << longestString.size()  << " characters\n";
   cout << longestString << endl;
   cout << backwards << endl;

   cout << endl;
   return 0;
}

//-----------------------------------
// Reverse
// Preconditions: none
// PostConditions:
//   returns the user supplied string
// in reverse character order
//-----------------------------------

string Reverse (string s)
{

   string result(s);           // copy of original string
   int start = 0;              // left-most character
   int end = s.length();       // right-most character
  

   // swap chars until end and start 
   // meet in the middle
   while (start < end)
   {
      --end;
      char c = result[end];
      result[end] = result[start];
      result[start] = c;
      ++start;
   }

   return result;

}