root directory in asp.net need not hard code

i am tryin to send mail to a user and providing him a authetication link to activate his account but i am hard coding the link. is there any way wh开发者_如何学Cere i need not hard code

string url = "http://localhost:3876/User/Authenticate-User.aspx?emailID=" + emailfield;

string msgBody = "<h3>Dear User</h3>" + "<p>Thanks for your interest, Kindly click on the URL below to authenticate</p><br>" +
                              "<a href='" + url + "'>Activate Link</a><br><br>" +
                              "\r\n<p>With Regards,<br>Team</p>";

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You can get the correct address for where a page is hosted using Request.Url

I find the "GetComponents" method most flexible in that you can see your options with Intellisense quite easily.

string serverAddress = "http://" + 
HttpContext.Current.Request.Url.GetComponents(UriComponents.Host, UriFormat.SafeUnescaped);
if (!string.IsNullOrEmpty(HttpContext.Current.Request.Url.GetComponents(UriComponents.Port, UriFormat.SafeUnescaped))) {
    serverAddress = serverAddress + ":" + HttpContext.Current.Request.Url.GetComponents(UriComponents.Port, UriFormat.SafeUnescaped);
}

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string ActivationLink=Request.Url.ToString().Substring(0, Request.Url.ToString().LastIndexOf('/')) + "/Authenticate-User.aspx?emailID=" + emailfield;