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Function to convert Arabic numbers into Roman Numerals



Function to convert Arabic numbers into Roman Numerals

Here's a little function I put together to convert an Arabic number between 0 and 9,999 to a 
Roman Numeral.  Initial testing went well, but it has not been fully tested yet. 

<? 
function to_roman($num) { 

// Function to convert an arabic number ($num) to a roman numeral.  $num must be between 
0 and 9,999 

if ($num < 0 || $num > 9999) { return -1; } // out of range 

$r_ones = array(1=> "I", 2=>"II", 3=>"III", 4=>"IV", 5=>"V", 6=>"VI", 7=>"VII", 8=>"VIII", 
9=>"IX"); 
$r_tens = array(1=> "X", 2=>"XX", 3=>"XXX", 4=>"XL", 5=>"L", 6=>"LX", 7=>"LXX", 
8=>"LXXX", 9=>"XC"); 
$r_hund = array(1=> "C", 2=>"CC", 3=>"CCC", 4=>"CD", 5=>"D", 6=>"DC", 7=>"DCC", 
8=>"DCCC", 9=>"CM"); 
$r_thou = array(1=> "M", 2=>"MM", 3=>"MMM", 4=>"MMMM", 5=>"MMMMM", 6=>"MMMMMM", 
7=>"MMMMMMM", 8=>"MMMMMMMM", 9=>"MMMMMMMMM"); 

$ones = $num % 10; 
$tens = ($num - $ones) % 100; 
$hundreds = ($num - $tens - $ones) % 1000; 
$thou = ($num - $hundreds - $tens - $ones) % 10000; 

$tens = $tens / 10; 
$hundreds = $hundreds / 100; 
$thou = $thou / 1000; 

if ($thou) { $rnum .= $r_thou[$thou]; } 
if ($hundreds) { $rnum .= $r_hund[$hundreds]; } 
if ($tens) { $rnum .= $r_tens[$tens]; } 
if ($ones) { $rnum .= $r_ones[$ones]; } 

return $rnum; 

} // function to_roman($num) 
?>