1   (  // brackets covering match for protocol (optional) and domain 2     ([A-Za-z]{3,9}:(?:\/\/)?) // match protocol, allow in format http:// or mailto: 3     (?:[\-;:&=\+\$,\w]+@)?    // allow something@ for email addresses 4     [A-Za-z0-9\.\-]+          // anything looking at all like a domain, non-unicode domains 5     |// or instead of above 6     (?:www\.|[\-;:&=\+\$,\w]+@) // starting with something@ or www. 7     [A-Za-z0-9\.\-]+            // anything looking at all like a domain 8   ) 9   ( // brackets covering match for path, query string and anchor10     (?:\/[\+~%\/\.\w\-]*)    // allow optional /path11     ?\??(?:[\-\+=&;%@\.\w]*) // allow optional query string starting with ? 12     #?(?:[\.\!\/\\\w]*)      // allow optional anchor #anchor13   )? // make URL suffix optional

 1 public static class ContentFormatter 2 { 3     private static readonly Regex Url_To_Link = new Regex(@"(?<url> 4         (https?:(?:\/\/)?)        # match protocol, allow in format http:// or https:// 5         [A-Za-z0-9\.\-]+          # anything looking at all like a domain, non-unicode domains         6         (                         # brackets covering match for path, query string and anchor 7         (?:\/[\+~%\/\.\w\-]*)?    # allow optional /path 8         \??(?:[\-\+=&;%@\.\w]*?)  # allow optional query string starting with ?  9         \#?(?:[\.\!\/\\\w\-]*)      # allow optional anchor #anchor10         )?                        # make URL suffix optional11         )",12         RegexOptions.Compiled | RegexOptions.Multiline | RegexOptions.IgnorePatternWhitespace,13         TimeSpan.FromMilliseconds(100));14 15     public static string UrlToLink(string text)16     {17         if (string.IsNullOrEmpty(text)) return string.Empty;18 19         return Url_To_Link.Replace(text, "<a href=http://www.mamicode.com/"${url}\" target=\"_blank\">${url}</a>");20     }21 }