Converting a List to string and vice-versa

Helper methods to convert a List to String and Vice-Versa

/// <summary>
/// Converts List to string with given separator.
/// </summary>
/// <param name="list">The list.</param>
/// <param name="separator">The separator.</param>
/// <returns></returns>
public static string ListToString(List<string> list,string separator)
{
     StringBuilder sb = new StringBuilder();




     foreach (string s in list)
     {
           sb.Append(string.Format("{0}{1}", s, separator));


     }  










     string returnString = string.Empty;  

     //Remove the last separator from the list
     if (sb.Length > 0)
     {
        returnString = sb.Remove(sb.ToString().LastIndexOf(separator), separator.Length).ToString();
     }  

     return returnString;
}

/// <summary>
/// Strings to string list.
/// </summary>
/// <param name="items">The items.</param>
/// <param name="separator">The separator.</param>
/// <returns></returns>
public static List<string> StringToStringList(string items, char separator)
{
      List<string> list = new List<string>();
      string[] listItmes = items.Split(separator); 

      foreach (string item in listItmes)
      {
          list.Add(item);
      } 

      if (list.Count > 0)
          return list;

      else 


          return null;
}