If you are using a repeater for binding the data from user end, you can use the following :
private void dataList_ItemDataBound(object sender, System.Web.UI.WebControls.DataGridItemEventArgs e)
{
if( (e.Item.ItemType == ListItemType.Item) || ( e.Item.ItemType == ListItemType.AlternatingItem))
{
HyperLink hyplnk = (HyperLink)e.Item.FindControl("lnkReadmore");
if (hyplnk.Text.length > 20 )
{
hyplnk.Text = hyplnk.Text.Substring(0,20);
}
}
}
If i misunderstand your question, please feel free to correct me.
I hope the above information will be helpful. If you have more concerns, please let me know.