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

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

using System.DirectoryServices.AccountManagement;

public string GetEmailIdFromActiveDirectory(string userName)
{
 var emailId = string.Empty;

 string activeDirectory_LDAP = "server";
 string activeDirectory_User = "ad_username";
 string activeDirectory_Password = "ad_password";

 PrincipalContext ctx = new PrincipalContext(ContextType.Domain, activeDirectory_LDAP);

 bool isCredentialsValid = ctx.ValidateCredentials(activeDirectory_User, activeDirectory_Password);

 if (isCredentialsValid)
 {
  UserPrincipal userPr = new UserPrincipal(ctx);
  userPr.SamAccountName = userName;

  PrincipalSearcher srchUser = new PrincipalSearcher(userPr);
  UserPrincipal foundUsr = srchUser.FindOne() as UserPrincipal;

  if (foundUsr != null)
  {
   emailId = foundUsr.Email;
  }
 }

 return emailId;
}