How to get Domain\users name in string type variable from sharepoint site into custom webpart

My query is i want to store a list of users from sharepoint site in string.

i have sp_user group that contain all the user of sp_group. I have another group Moss_2007Admin that have admin users. How can i get all users name e.g. "Domain\username;Domain\username1;Domain\username2" into string type variable that i am g开发者_如何学运维oing to use in my custom webpart.

Please help on this. Thanks.

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Top of my head and have not checked in compiler :-

private string listUsers(SPGroup group)
{
   StringBuilder sb = new StringBuilder()
   foreach (SPUser user in group)
      sb.AppendFormat("{0};",user.LoginName);

   return sb.ToString();
}

See SPUser