这篇文章主要介绍了php实现阿拉伯数字和罗马数字相互转换的方法,涉及php字符串操作的相关技巧,具有一定参考借鉴价值,需要的朋友可以参考下,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：

1. <?php
2. // Function that calculates the roman string to the given number:
3. function dec2roman($f)
4. {
5. // Return false if either $f is not a real number,
6. //$f is bigger than 3999 or $f is lower or equal to 0:
7. if(!is_numeric($f) || $f > 3999 || $f <= 0) return false;
8. // Define the roman figures:
9. $roman = array(
10. 'M' => 1000,
11. 'D' => 500,
12. 'C' => 100,
13. 'L' => 50,
14. 'X' => 10,
15. 'V' => 5,
16. 'I' => 1
17. );
18. // Calculate the needed roman figures:
19. foreach($roman as $k => $v)
20. if(($amount[$k] = floor($f / $v)) > 0)
21. $f -= $amount[$k] * $v;
22. // Build the string:
23. $return = '';
24. foreach($amount as $k => $v)
25. {
26. $return .= $v <= 3 ? str_repeat($k, $v) : $k . $old_k;
27. $old_k = $k;
28. }
29. // Replace some spacial cases and return the string:
30. return str_replace(array('VIV','LXL','DCD'),array('IX','XC','CM'),$return);
31. }
32. // echo dec2romen(1981);
33. // Function to get the decimal value of a roman string:
34. function roman2dec($str = '')
35. {
36. // Return false if not at least one letter is in the string:
37. if(is_numeric($str)) return false;
38. // Define the roman figures:
39. $roman = array(
40. 'M' => 1000,
41. 'D' => 500,
42. 'C' => 100,
43. 'L' => 50,
44. 'X' => 10,
45. 'V' => 5,
46. 'I' => 1
47. );
48. // Convert the string to an array of roman values:
49. for($i = 0; $i < strlen($str); $i++)
50. if(isset($roman[strtoupper($str[$i])]))
51. $values[] = $roman[strtoupper($str[$i])];
52. // Calculate the sum of that array:
53. $sum = 0;
54. while($current = current($values))
55. {
56. $next = next($values);
57. $next > $current ? $sum += $next - $current + 0 * next($values) : $sum += $current;
58. }
59. // Return the value:
60. return $sum;
61. }
62. // echo roman2dec(IX);
63. ?>