Converts an Arabic Numeral to Roman Numeral. Works for 1 through 4999.

roman_numerals_helper.php

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');

/*
 
	|----------------------------------------------------------------
	| Description
	|----------------------------------------------------------------
 
		Converts an Arabic Numeral to Roman Numeral.

		Works for 1 through 4999.
 
 
	|----------------------------------------------------------------
	| Dependencies
	|----------------------------------------------------------------
 
		CodeIgniter
 
 
	|----------------------------------------------------------------
	| Example Usage
	|----------------------------------------------------------------
 
 		<?php

			echo roman_numerals(14);

		?>

			Should print the following:

				XIV
 
*/

function roman_numerals($input_arabic_numeral)
{
	if (empty($input_arabic_numeral))
		return false;

	$arabic_numeral = (int) $input_arabic_numeral;
	$arabic_numeral_text = (string) $arabic_numeral;
	$arabic_numeral_length = strlen($arabic_numeral_text);

	if (preg_match('~[0-9]~', $arabic_numeral_text) !== 1)
		return false;

	if ($arabic_numeral_length > 4)
		return false;

	if ($arabic_numeral > 4999)
		return false;

	if ($arabic_numeral < 1)
		return false;

	$roman_numeral_units = array();
	$roman_numeral_tens = array();
	$roman_numeral_hundreds = array();
	$roman_numeral_thousands = array();

	/*
		No zeroes in Roman Numerals.
	*/
	$roman_numeral_units[0] = '';
	$roman_numeral_tens[0] = '';
	$roman_numeral_hundreds[0] = '';
	$roman_numeral_thousands[0] = '';

	$roman_numeral_units[1]='I';
	$roman_numeral_units[2]='II';
	$roman_numeral_units[3]='III';
	$roman_numeral_units[4]='IV';
	$roman_numeral_units[5]='V';
	$roman_numeral_units[6]='VI';
	$roman_numeral_units[7]='VII';
	$roman_numeral_units[8]='VIII';
	$roman_numeral_units[9]='IX';

	$roman_numeral_tens[1]='X';
	$roman_numeral_tens[2]='XX';
	$roman_numeral_tens[3]='XXX';
	$roman_numeral_tens[4]='XL';
	$roman_numeral_tens[5]='L';
	$roman_numeral_tens[6]='LX';
	$roman_numeral_tens[7]='LXX';
	$roman_numeral_tens[8]='LXXX';
	$roman_numeral_tens[9]='XC';

	$roman_numeral_hundreds[1]='C';
	$roman_numeral_hundreds[2]='CC';
	$roman_numeral_hundreds[3]='CCC';
	$roman_numeral_hundreds[4]='CD';
	$roman_numeral_hundreds[5]='D';
	$roman_numeral_hundreds[6]='DC';
	$roman_numeral_hundreds[7]='DCC';
	$roman_numeral_hundreds[8]='DCCC';
	$roman_numeral_hundreds[9]='CM';

	$roman_numeral_thousands[1]='M';
	$roman_numeral_thousands[2]='MM';
	$roman_numeral_thousands[3]='MMM';
	$roman_numeral_thousands[4]='MMMM';

	if ($arabic_numeral_length == 3) { $arabic_numeral_text = "0" . $arabic_numeral_text; }
	if ($arabic_numeral_length == 2) { $arabic_numeral_text = "00" . $arabic_numeral_text; }
	if ($arabic_numeral_length == 1) { $arabic_numeral_text = "000" . $arabic_numeral_text; }

	$anu = substr($arabic_numeral_text, 3, 1);
	$anx = substr($arabic_numeral_text, 2, 1);
	$anc = substr($arabic_numeral_text, 1, 1);
	$anm = substr($arabic_numeral_text, 0, 1);

	$roman_numeral_text = $roman_numeral_thousands[$anm];
	$roman_numeral_text .= $roman_numeral_hundreds[$anc];
	$roman_numeral_text .= $roman_numeral_tens[$anx];
	$roman_numeral_text .= $roman_numeral_units[$anu];

	return $roman_numeral_text;
}


/* End of file roman_numerals_helper.php */
/* Location: ./application/helpers/roman_numerals_helper.php */