Reputation: 413

Numbers to Roman Numbers with php

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

        <?php

function roman2number($roman){
    $conv = array(
        array("letter" => 'I', "number" => 1),
        array("letter" => 'V', "number" => 5),
        array("letter" => 'X', "number" => 10),
        array("letter" => 'L', "number" => 50),
        array("letter" => 'C', "number" => 100),
        array("letter" => 'D', "number" => 500),
        array("letter" => 'M', "number" => 1000),
        array("letter" => 0, "number" => 0)
    );
    $arabic = 0;
    $state = 0;
    $sidx = 0;
    $len = strlen($roman);

    while ($len >= 0) {
        $i = 0;
        $sidx = $len;

        while ($conv[$i]['number'] > 0) {
            if (strtoupper(@$roman[$sidx]) == $conv[$i]['letter']) {
                if ($state > $conv[$i]['number']) {
                    $arabic -= $conv[$i]['number'];
                } else {
                    $arabic += $conv[$i]['number'];
                    $state = $conv[$i]['number'];
                }
            }
            $i++;
        }

        $len--;
    }

    return($arabic);
}


function number2roman($num,$isUpper=true) {
    $n = intval($num);
    $res = '';

    /*** roman_numerals array ***/
    $roman_numerals = 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 ($roman_numerals 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 res ***/
    if($isUpper) return $res;
    else return strtolower($res);
}

/* TEST */
echo $s=number2roman(6,true);
echo "\n and bacK:\n";
echo roman2number($s);


?>

try this way but does not work:

echo $s=number2roman((.$row['id'].),true);
echo "\n and bacK:\n";
echo roman2number($s);

the problem is that I need to change numbers are readings of my sql database and do not know how to, from and through.

Upvotes: 41

Answers (9)

Jim

Reputation: 3609

You can format integers into Roman numeral symbols with the ICU intl library's NumberFormatter class by setting the locale parameter to @numbers=roman with decimal style format:

function intToRomanNumeral(int $num) {
    static $nf = new NumberFormatter('@numbers=roman', NumberFormatter::DECIMAL);
    return $nf->format($num);
}

Output examples:

echo intToRomanNumeral(2); // II

echo intToRomanNumeral(5); // V

echo intToRomanNumeral(10); // X

echo intToRomanNumeral(50); // L

echo intToRomanNumeral(57); // LVII
echo intToRomanNumeral(58); // LVIII

echo intToRomanNumeral(100); // C

echo intToRomanNumeral(150); // CL

echo intToRomanNumeral(1000); // M

echo intToRomanNumeral(10000); // ↂ

Alternatively, you can use the MessageFormatter class, but in my own testing it appears to have significantly lower performance than NumberFormatter:

function intToRomanNumeral(int $num) {
    static $nf = new MessageFormatter('@numbers=roman', '{0, number}');
    return $nf->format([$num]);
}

Upvotes: 7

mickmackusa

Reputation: 47991

While appreciate the succinct mathematical nested loop approach posted by @user2095686, I agree more with @HaiderLasani's approach of writing the foreach() as the outer loop because it never unnecessarily revisits previously processed elements in the translation array. Haider's answer does not explain why this adjustment is ideal. I've created a demo to echo out all of the unnecessary conditional checks that @user2095686's answer makes. Gone one step further than @Haider's answer, I've written a condition inside of the while() loop to break both loops as soon as the modified input integer is reduced to zero.

Code: (Demo)

function numberToRoman(int $integer): string {
    static $conversions = [
        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'
    ];
    $romanString = '';
    foreach ($conversions as $int => $roman) {
        while ($integer >= $int) {
            $integer -= $int;
            $romanString .= $roman;
            if (!$integer) {
                break 2;
            }
        }
    }
    return $romanString;
}

If you are not turned off by the style of performing assignment arithmetic inside of a conditional expression, the script can be condensed a little more...

foreach ($conversions as $int => $roman) {
    while ($integer >= $int) {
        $romanString .= $roman;
        if (!($integer -= $int)) {
            break 2;
        }
    }
}

Upvotes: 0

Wojciech Brüggemann

Reputation: 1

My own function it has the best performance:

function romanNumber($n)
{
    // support for numbers greater than a thousand
    $ret1 = '';
    while ($n >= 1000) {
        $ret1 .= 'M';
        $n -= 1000;
    }

    $ret = '';
    if ($n > 0) {
        $n = (string) $n;
        $l = 'IVXLCDM';
        $j = 0; // goes by roman letters
        for ($i = strlen($n)-1; $i >= 0; --$i) { // goes by decimal number
            switch ($n[$i]) {
                case 0: $s = ''; break;
                case 1: $s = $l[$j]; break;
                case 2: $s = $l[$j].$l[$j]; break;
                case 3: $s = $l[$j].$l[$j].$l[$j]; break;
                case 4: $s = $l[$j].$l[$j+1]; break;
                case 5: $s = $l[$j+1]; break;
                case 6: $s = $l[$j+1].$l[$j]; break;
                case 7: $s = $l[$j+1].$l[$j].$l[$j]; break;
                case 8: $s = $l[$j+1].$l[$j].$l[$j].$l[$j]; break;
                case 9: $s = $l[$j].$l[$j+2]; break;
            }
            $j += 2;
            $ret = $s.$ret;
        }
    }

    return $ret1.$ret;
}

Upvotes: 0

Wojciech Brüggemann

Reputation: 1

I improve rome() function of Jasiek

function rome2($N)
{
    // support for numbers greater than a thousand
    $ss = '';
    while ($N > 1000) {
        $ss .= 'M';
        $N -= 1000;
    }

    $c = 'IVXLCDM';
    for ($a = 5, $b = 0, $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 $ss.$s;
}

Upvotes: 0

user2095686

Reputation:

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;
}

Upvotes: 98

Haider Lasani

Reputation: 169

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;
    }

Upvotes: 1

frostymarvelous

Reputation: 2805

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 <[email protected]>
     * @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;

        }


    }

Upvotes: -4

Jasiek

Reputation: 59

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

Upvotes: 5

Muhammad Tahir

Reputation: 2485

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); 
?>

Upvotes: 6

Numbers to Roman Numbers with php

Answers (9)

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