List the groups for the specified user in C# using ADSI.

Using the ADSI IADsUser class and it's 'Groups' method to get a list of groups of which the user is a member is fairly simple once you know the trick.

First, you will have to add a reference to the 'Active Directory DS' COM object.
Second, add the statement: using ActiveDS;

Here is a GroupNames() function to demo the process:

using ActiveDS;

public static string[] GroupNames(string userName)
{
   List result = new List(20);
   if (String.IsNullOrEmpty(userName) == true)
   {
      return null;
   }


   userName = userName.Trim().Replace('\\', '/');


   DirectoryEntry de = new DirectoryEntry(String.Format("WinNT://{0},user", userName));


   IADsMembers groupsForUser = (IADsMembers) de.Invoke("Groups",null);


   foreach (object group in groupsForUser)
   {
      DirectoryEntry deGroup = new DirectoryEntry(group);
      result.Add(deGroup.Name);
   }


   if (result.Count == 0)
   {
      return null;
   }
   
   return result.ToArray();
}