using Microsoft.SharePoint;

private function bool siteUsers()
{
    SPSite siteCollection = new SPSite("http://localhost/");
    SPUserCollection SPUsers = siteCollection.AllWebs["/"].Users;  // root site

    foreach (SPUser SPUser in SPUsers)
    {
        Console.Write(SPUser.Name + "\r\n");
    }

    return true; 

}

private function doFoobar()
{ 

    Delete/Update SharePoint list items...

    SPSite siteCollection = new SPSite("http://localhost/");
    System.Net.NetworkCredential auth = new System.Net.NetworkCredential("userName", "password", "domain");
    siteCollection.credentials = auth;
    SPList list = siteCollection.AllWebs["sub_web_x"].Lists["List_Name"];
    /**********************************************
    Delete Existing SP list items
    **********************************************/
    SPQuery query = new SPQuery();
    query.Query = "";  // Send no conditions in query.  (btw, this is a CAML query type)
    SPListItemCollection listItems = list.GetItems(query);
    int listItemsCount = listItems.Count;

    for (int i = 0; i < listItemsCount; i++)
    {
        listItems.Delete(0);  // becuase the index slides as items are deleted, we simply delete the 0 index item repeatedly.
    }

    /**********************************************
    Load up records from a db table
    **********************************************/
    SqlConnection conn = new SqlConnection();
    SqlCommand cmd = new SqlCommand();
    conn.ConnectionString = "Data Source=db_Server;User ID=foo;Password=bar;Database=personel_db";
    conn.Open();
    cmd.Connection = conn;
    cmd.CommandType = CommandType.Text;
    cmd.CommandText = "SELECT * FROM vContacts";
    SqlDataReader dataReader = cmd.ExecuteReader();
    // Load up records into SharePoint lists.
    int x = 0;

    while (dataReader.Read())
    {
        SPListItem newItem = listItems.Add();
        newItem["Last Name"] = dataReader["LastName"];
        newItem["First Name"] = dataReader["FirstName"];
        newItem["Middle Initial"] = dataReader["Minitial"];
        newItem["Nickname"] = dataReader["NickName"];
        newItem["Company"] = dataReader["Company"];
        newItem["Department"] = dataReader["Department"];
        newItem["Customer Phone"] = dataReader["CustomerPhone"];
        newItem["TEAS Office Phone"] = dataReader["TEASPhone"];
        newItem["E-mail Address"] = dataReader["EmpEmail"];
        newItem["Username"] = dataReader["UserName"];
        newItem.Update();
    }
    conn.Close();

    return true;
}