实例一：
string result = "";
string str = "大家好! <User EntryTime=‘2010-10-7‘ Email=‘[email protected]‘>张三</User> 自我介绍。";
Regex regex = new Regex(@"<User\s*EntryTime=‘(?<time>[\s\S]*?)‘\s+Email=‘(?<email>[\s\S]*?)‘>(?<userName>[\s\S]*?)</User>", RegexOptions.IgnoreCase);
Match match = regex.Match(str);
if (match.Success)
{
string userName = match.Groups["userName"].Value; //获取用户名
string time = match.Groups["time"].Value; //获取入职时间
string email = match.Groups["email"].Value; //获取邮箱地址
string strFormat = String.Format("我是：{0}，入职时间：{1}，邮箱：{2}", userName, time, email);
result = regex.Replace(str, strFormat); //替换内容
Console.WriteLine(result);
}
实例二：
var s = "http://www.baidu.com/articles/2018/3/15/sss.html";
var reg = new Regex(@"articles/(?<date>\d{4}/\d{1,2}/\d{1,2})/", RegexOptions.IgnoreCase);
Match _match = reg.Match(s);
if (_match.Success)
{
Console.WriteLine(_match.Groups["date"]);
}