How to get the Expiration Date of an Active Directory User

This code snippet explains that how can you get the expiration date of an active directory user.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.DirectoryServices;
using Microsoft.VisualBasic;
namespace AD
{
class Program
{
static public void Main(string[] args)
{
DirectoryEntry user = new DirectoryEntry("LDAP://CN=" + username + "," + " OU= Web Users,DC=SERVERNAME,DC=com", null, null, AuthenticationTypes.Secure);
DateTime expires = DateTime.FromFileTime(GetInt64(user, "accountExpires"));
string expDate = expires.ToShortDateString();
Console.WriteLine(expDate.ToString());
string exp = expires.ToLongDateString();
Console.WriteLine(exp.ToString());
Console.WriteLine(expires.ToString());
Console.ReadKey();
}
static string username = "testADuser1";
static public Int64 GetInt64(DirectoryEntry entry, string attr)
{
//we will use the marshaling behavior of
//the searcher
DirectorySearcher ds = new DirectorySearcher(
entry,
String.Format("({0}=*)", attr),
new string[] {attr},
SearchScope.Base);
SearchResult sr = ds.FindOne();
if (sr != null)
{
if (sr.Properties.Contains(attr))
{
return (Int64) sr.Properties[attr][0];
}
}
return -1;
}
}
}