php实现阿拉伯数字和罗马数字相互转换的方法

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。