Numbers to Roman Numbers with php

Question

I need to transform ordinary numbers to Roman numerals with php and I have this code:

Answer 1

Check out my solution here https://github.com/frostymarvelous/Whisppa-Libs/blob/master/Misc/Numeralo.php . It works both ways.

    <?php
     /**
     * @package    Whisppa
     * @subpackage Misc
     * @license    http://opensource.org/licenses/MIT  MIT License
     * @author     Stefan (frostymarvelous) Froelich <sfroelich@gmail.com>
     * @copyright  Copyright (c) 2015, Stefan (frostymarvelous) Froelich
     */
    namespace Whisppa\Misc;


    /**
     * This class allows you to convert from Roman numerals to natural numbers and vice versa.
     * I decided to do this as a fun challenge after reading http://thedailywtf.com/articles/Roman-Enumeration
     * Took me about 30 minutes to come up with, research and code the solution.
     * It can convert numbers up to 3,999,999 because I couldn't find any numerals for 5,000,000 above.
     * Due to my inability to get the correct accented characters 5000 above, I resulted to using the pipe (|) to represent accent. 
     */
    class Numeralo
    {
        /**
        * @var string[] A notation map to represent the common Roman numeral values. 
        * @static
        */
        protected static $NOTATION = 
        [
            '|', //one
            '[', //five
            ']', //ten
        ];

        /**
        * @var \ArrayObject[] A map of Roman numerals based on place value. Each item ends with the first numeral in the next place value.
        * @static
        */
        protected static $NUMERALS_BY_PLACE_VALUE =     
        [
            ['I', 'V', 'X',], //ones
            ['X', 'L', 'C',], //tens
            ['C', 'D', 'M',], // hundreds
            ['M', 'V|', 'X|',], //thousands
            ['X|', 'L|', 'C|',], //tens of thousands
            ['C|', 'D|', 'M|',], //hundreds of thousands
            ['M|', '~', '~',], // millions. there are no values for the last two that I could find
        ];

        /**
        * @var string[]  sA map of numbers and their representative Roman numerals in notation format. This map allows us to make any numeral by replacing the the notation with the place value equivalent.    
        * @static
        */
        protected static $NUMBER_TO_NOTATION = 
        [
            '0' => '',
            '1' => '|',
            '2' => '||',
            '3' => '|||',
            '4' => '|[',
            '5' => '[',
            '6' => '[|',
            '7' => '[||',
            '8' => '[|||',
            '9' => '|]',
        ];

        /**
        * @var int[] A map of the major Roman numerals and the number equivalent.
        * @static
        */
        protected static $NUMERALS_TO_NUMBER = 
        [
            'I' => 1,
            'V' => 5,
            'X' => 10,
            'L' => 50,
            'C' => 100,
            'D' => 500,
            'M' => 1000,
            'V|' => 5000,
            'X|' => 10000,
            'L|' => 50000,
            'C|' => 100000,
            'D|' => 500000,
            'M|' => 1000000,
        ];

        /**
        * Converts natural numbers to Roman numerals.
        *
        * @static
        * @param int|string $number a number or numeric string less than 3,999,999
        * @throws \InvalidArgumentException if the provided $number argument is not numeric or greater than 3,999,999.
        * @return string Roman numeral equivalent   
        */
        public static function number_to_numerals($number) {
            if(!is_numeric($number))
                throw new \InvalidArgumentException('Only numbers allowed');
            if($number > 3999999)
                throw new \InvalidArgumentException('Number cannot be greater than 3,999,999');


            $numerals = '';
            $number_string = strrev((string) $number);
            $length = strlen($number_string);

            for($i = 0; $i < $length; $i++) {
                $char = $number_string[$i];

                $num_map = self::$NUMERALS_BY_PLACE_VALUE[$i];
                $numerals = str_replace(self::$NOTATION, $num_map, self::$NUMBER_TO_NOTATION[$char]) . $numerals;
            }

            return $numerals;   
        }

        /**
        * Converts Roman numerals to natural numbers.
        *
        * @static
        * @param string $numerals the Roman numerals to be converted
        * @throws \InvalidArgumentException if the provided $numerals argument contains invalid characters.
        * @return int the equivalent number
        */
        public static function numerals_to_number($numerals) {
            $number = 0;
            $numeral_string = strrev((string) $numerals);
            $length = strlen($numeral_string);

            $prev_number = false;
            $is_accented = false;

            for($i = 0; $i < $length; $i++) {
                $char = $numeral_string[$i];

                if($char == '|') //check if it is an accent character
                {
                    $is_accented = true;
                    continue;//skip this iteration and process it in the next one as the accent applies to the next char
                }
                else if($is_accented)
                {
                    $char .= '|';
                    $is_accented = false;
                }

                //TODO Make a check using maybe regex at the beginning of the method.
                if(!isset(self::$NUMERALS_TO_NUMBER[$char]))
                    throw new \InvalidArgumentException("Invalid character '{$char}' in numeral string");


                $num = self::$NUMERALS_TO_NUMBER[$char];

                //this is where the magic happens
                //if the previous number divided by 5 or 10 is equal to the current number, then we subtract eg. 9 = IX. I = 1, X = 10, 10/10 = 1
                if($prev_number)
                {
                    if(($prev_number / 5) == $num || ($prev_number / 10) == $num)
                        $number -= $num;
                    else
                        $number += $num;
                }
                else
                    $number += $num;


                $prev_number = $num;
            }

            return $number;

        }


    }

Answer 2

CHECKED AND VERIFIED BY PHP UNIT

Make a class having name RomanNumerials and add a protected static property as defined:

protected static $lookup = [
        1000 => 'M',
        900 => 'CM',
        500 => 'D',
        400 => 'CD',
        100 => 'C',
        90 => 'XC',
        50 => 'L',
        40 => 'XL',
        10 => 'X',
        9 => 'IX',
        5 => 'V',
        4 => 'IV',
        1 => 'I',
    ];

then add a method as follows

public function output ($number)
    {
        $solution = '';

        foreach(static::$lookup as $limit => $glyph){
            while ($number >= $limit) {
                $solution .= $glyph;
                $number -= $limit;
            }
        }

        return $solution;
    }

Answer 3

Another way to do that

<?php 
function ConverToRoman($num){ 
    $n = intval($num); 
    $res = ''; 

    //array of roman numbers
    $romanNumber_Array = array( 
        'M'  => 1000, 
        'CM' => 900, 
        'D'  => 500, 
        'CD' => 400, 
        'C'  => 100, 
        'XC' => 90, 
        'L'  => 50, 
        'XL' => 40, 
        'X'  => 10, 
        'IX' => 9, 
        'V'  => 5, 
        'IV' => 4, 
        'I'  => 1); 

    foreach ($romanNumber_Array as $roman => $number){ 
        //divide to get  matches
        $matches = intval($n / $number); 

        //assign the roman char * $matches
        $res .= str_repeat($roman, $matches); 

        //substract from the number
        $n = $n % $number; 
    } 

    // return the result
    return $res; 
} 

echo ConverToRoman(23); 
?>

Answer 4

function rome($N){
    $c='IVXLCDM';
    for($a=5,$b=$s='';$N;$b++,$a^=7)
        for($o=$N%$a,$N=$N/$a^0;$o--;$s=$c[$o>2?$b+$N-($N&=-2)+$o=1:$b].$s);
    return $s;
}

// from polish wiki

Answer 5

There is an illegal offset issue.

Replace

$o=1:$b].$s);

with

$o=1:$b >0 ? $b : 0].$s);

Answer 6

I found this code here: http://php.net/manual/en/function.base-convert.php

Optimized and prettified function:

/**
 * @param int $number
 * @return string
 */
function numberToRomanRepresentation($number) {
    $map = array('M' => 1000, 'CM' => 900, 'D' => 500, 'CD' => 400, 'C' => 100, 'XC' => 90, 'L' => 50, 'XL' => 40, 'X' => 10, 'IX' => 9, 'V' => 5, 'IV' => 4, 'I' => 1);
    $returnValue = '';
    while ($number > 0) {
        foreach ($map as $roman => $int) {
            if($number >= $int) {
                $number -= $int;
                $returnValue .= $roman;
                break;
            }
        }
    }
    return $returnValue;
}