// Function that calculates the roman string to the given number:
function dec2roman($f)
{
// Return false if either $f is not a real number, $f is bigger than 3999 or $f is lower or equal to 0:
if(!is_numeric($f) || $f > 3999 || $f <= 0) return false;
// Define the roman figures:
$roman = array('M' => 1000, 'D' => 500, 'C' => 100, 'L' => 50, 'X' => 10, 'V' => 5, 'I' => 1);
// Calculate the needed roman figures:
foreach($roman as $k => $v) if(($amount[$k] = floor($f / $v)) > 0) $f -= $amount[$k] * $v;
// Build the string:
$return = '';
foreach($amount as $k => $v)
{
$return .= $v <= 3 ? str_repeat($k, $v) : $k . $old_k;
$old_k = $k;
}
// Replace some spacial cases and return the string:
return str_replace(array('VIV','LXL','DCD'), array('IX','XC','CM'), $return);
}
// echo dec2romen(1981);
// Function to get the decimal value of a roman string:
function roman2dec($str = '')
{
// Return false if not at least one letter is in the string:
if(is_numeric($str)) return false;
// Define the roman figures:
$roman = array('M' => 1000, 'D' => 500, 'C' => 100, 'L' => 50, 'X' => 10, 'V' => 5, 'I' => 1);
// Convert the string to an array of roman values:
for($i = 0; $i < strlen($str); $i++) if(isset($roman[strtoupper($str[$i])])) $values[] = $roman[strtoupper($str[$i])];
// Calculate the sum of that array:
$sum = 0;
while($current = current($values))
{
$next = next($values);
$next > $current ? $sum += $next - $current + 0 * next($values) : $sum += $current;
}
// Return the value:
return $sum;
}
// echo roman2dec(IX);
?>