How to get a value from Active Directory using C# DirectoryEntry Class

Here is a sample C# program to get email id from active directory by username using DirectorySearcher class.

using System.DirectoryServices;

public string GetEmailIdFromActiveDirectory(string userName)
{
 
 var emailId = string.Empty;
 
 string activeDirectory_LDAP = "LDAP://server";
 
 string activeDirectory_User = "ad_username";
 
 string activeDirectory_Password = "ad_password";
 
 var directoryEntry = new DirectoryEntry(activeDirectory_LDAP, activeDirectory_User, activeDirectory_Password) { AuthenticationType = AuthenticationTypes.Secure };
 
 var directorySearcher = new DirectorySearcher(directoryEntry);
 
 directorySearcher.Filter = "sAMAccountName=" + userName;
 
 directorySearcher.SearchScope = SearchScope.Subtree;
 
 
 
 SearchResult searchResult = directorySearcher.FindOne();
 
 if (searchResult != null)
 
 {
 
  emailId = searchResult.GetDirectoryEntry().Properties["email"].Value.ToString();
 
 }
 
 
 
 return emailId;
 
}