这个正则怎么写

Question

格式如这样的：<img src="http://A/B/C"  border="1" align="left" class="student" /></a>
想取到值C，其中A和B是固定的，就向时http://www.123.com/files/1.jpg,那么A就是http://www.123.com/，B就是files,c酒是1.jpg，也就是我想要的，请问这个正则怎么写，谢了！

Answer 1

                string str = "<img src=\"http://www.123.com/files/1.jpg\" border=\"1\" align=\"left\" class=\"student\" /></a>";
                Regex reg = new Regex(@"(?is)<img[^>]*?src=(['""\s]?)http://www.123.com/files/([^'""\s]+)\1[^>]*?>");
                foreach (Match m in reg.Matches(str))
                    Console.WriteLine(m.Groups[2].Value);

Answer 2

                string src = @"<img src=""http://www.123.com/files/1.jpg"" border=""1"" align=""left"" class=""student"" /><img src=""http://www.123.com/files/2.jpg"" border=""1"" align=""left"" class=""student"" />";
                Regex re = new Regex(@"src=""(?<http>[^""]+?)/(?<f2>[^/]+?)/(?<f3>[^/]+?)""", RegexOptions.IgnoreCase);
                Match mc = re.Match(src);
                while( mc.Success)
                {
                    Response.Write(mc.Groups["http"]);
                    Response.Write("<br/>");
                    Response.Write(mc.Groups["f2"]);
                    Response.Write("<br/>");
                    Response.Write(mc.Groups["f3"]);
                    Response.Write("<br/>*************************<br/>");
                    mc = mc.NextMatch();
                   
                }
                Response.End();

Answer 3

简单点：<img.*www\.123\.com\/files\/(\w+\.\w+)