How to separate objects in a hidden input?

How to separate objects in a hidden input?

I have a hidden input that contains some objects in it. I put string "#"
between any two objects, but I want to put a string that isn't on
keyboard. How can I do it?
for (int i = 0; i < MyTable.Rows.Count; i++)
{
txtRows.Value += MyTable.Rows[i]["Row"].ToString();
if (i < MyTable.Rows.Count - 1)
{
txtRows.Value += "#";
}
}