Decimal to Roman numbers

chris — Wed, 05 Aug 2009 07:37:21 +0000

I needed a function to translate from decimal numbers to their Roman number equivalent. Here’s a handy little function I found.

private function numberToRoman($num)
{
     $n = intval($num);
     $result = '';
 
     $lookup = 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 ($lookup as $roman => $value) {
       $matches = intval($n / $value);
       $result .= str_repeat($roman, $matches);
       $n = $n % $value;
     }
     return $result;
}

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Decimal to Roman numbers