求助一个正则表达式

Question

求助一个正则表达式(C#),将1111.txt这个文件名取出来
http://localhost:3766/filedownload?s=Files%5c642&p=1&f=11222&o=1111.txt&pr=d
正则表达式C#

Answer 1

(?is)(?<=(&o=)).*(?=(&))

Answer 2

            string test1 = "http://localhost:3766/filedownload?s=Files%5c642&p=1&f=11222&o=1111.txt&pr=d";
            string test2 = "http://localhost:3766/filedownload?s=Files%5c642&p=1&f=11222&pr=d&o=1111.txt";            Regex regex = new Regex(".*o=(?<o>[^&]*).*");
            
            Match m1 = regex.Match(test1);
            Match m2 = regex.Match(test2);            Console.WriteLine(m1.Groups["o"].Value);
            Console.WriteLine(m2.Groups["o"].Value);

Answer 3

string filename = "http://localhost:3766/filedownload?s=Files%5c642&p=1&f=11222&o=1111.txt&pr=d".split('&')[2]

Answer 4

 string patten="&o=([^&]*)&";

Answer 5

原来是为了以后的拓展
            string urlstr = "http://localhost:3766/filedownload?s=Files%5c642&p=1&f=11222&o=1111.txt&pr=d";
            var filenames = urlstr.Split(new char[] { '&' }, StringSplitOptions.RemoveEmptyEntries).ToDictionary(x => x.Split('=')[0], p => p.Split('=')[1]);
            Console.WriteLine(filenames["o"]);
            Console.Read();