Dim sDecoded As String
Dim nLen As Long
nLen  = 777
    ...
sDecoded = String((nLen \ 4) * 3, " ")

   static void Main(string[] args)
        {
            string sDecoded = StringVb(3, " ");

            Console.WriteLine(sDecoded);
            Console.ReadKey();
        }

        protected static string StringVb(int cnt, object obj)
        {
            StringBuilder sb = new StringBuilder();

            for (int i = 0; i <= cnt; i++)
            {
                if (obj is Int32)
                {
                    sb.Append( Convert.ToChar(obj));
                }
                else if (obj is Char || obj is String)
                {
                     sb.Append(obj);
                } 
            }
            return sb.ToString();
        }