<?  // -*-Mode: c++;-*-

/*  
	PhpGa - PHP Genetic Algorithm Class Library
  Copyright (C) 2000 Bill C. White

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

/*
	BitString.inc - Bill White - 7/20/00

	This class is used to perform operations on a binary string. 
	Its original intent is to support the PhpGa genetic algorithm class.
*/
class BitString
{
	// class data members

	// set this flag to "1" for debugging output
	var $debug = 0;

	// string parameters
	var $myLength;
	var $myString;

	// class methods

	/* 
		 BitString - constructor
		 $initializer = string literal initializer
	*/
	function BitString($length, $initializer="") 
	{
		// bounds check specified string length
		if($length < 1 || $length > 128) {
			echo "BitString constructor: specified length: $length, ";
			echo "is outside the bounds 1 < length <= 128.<br>\n";
			exit;
		}

		// if no initializer, make random string
		if($initializer == "") {
			$this->myString = "";
			// assume random number generator has been appropriately seeded
			for($i=0; $i < $length; $i++) {
				$this->myString .= rand(0,1);
			}
		}
		else {
			// check that specified length and initializer string length are the same
			if($length == strlen($initializer)) {
				$this->myString = $initializer;
			}
			else {
				echo "BitString constructor: specified length: $length, ";
				echo "does not match length of initializer: $initializer.<br>\n";
				exit;
			}
		}

		// length is okay here; checked above
		$this->myLength = $length;
		
		if($this->debug) { echo "In BitString constructor:<br>string: $this->myString, length: $this->myLength<br>\n"; }
	}

	// return the number of zeroes and ones in the string
	function ZeroesAndOnesCount() 
	{
		$onesCount = 0;
		$zeroesCount = 0;
		for($i=0; $i < $this->myLength; $i++) {
			$thisChar = substr($this->myString, $i, 1);
			if($thisChar == "0") {
				$zeroesCount++;
			}
			else {
				$onesCount++;
			}
		}
		return array($zeroesCount, $onesCount);
	}

	function EmitAsHTML()
	{
		echo "$this->myString";
	}

} // end of class definition

?>