php实现阿拉伯数字和罗马数字相互转换的方法

<?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); ?>