C# - Get Binding Column Name Of Templatefield's Texbox

In ASP.net, I'm using textbox in templatefield's itemtemplate. I got it data-bound with no problem. But my problem is, I'm trying to write a function to find column index by its data-bounding table's column name.

Something like this :

foreach (DataControlFieldCell cell in row.Cells)
{
if (cell.ContainingField is BoundField)
{
if (((BoundField)cell.ContainingField).DataField.Equals(SearchColumnName))
{
return columnIndex;
}
}
else if (cell.ContainingField is TemplateField)
{
//Finding column name of data-bound textbox or dropdownlist ??
}
}