本文实例讲述了php实现阿拉伯数字和罗马数字相互转换的方法。分享给大家供大家参考。具体如下：

<?php// 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);  ?>

希望本文所述对大家的php程序设计有所帮助。