Assign a variable to backcolor control

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C#

ASP.NET

Hi, I am doing a conditional formatting on my gridview.

protected void OnRowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
      
{
string tileInput = Convert.ToString(e.Row.Cells[1].Text);//This retrieved from user input (TextBox) and now its output in gridview, at row 1

string tileDB = Convert.ToString(e.Row.Cells[0].Text); //This is retrieved from database and now its output in gridview, at row 0

if (tileInput == tileDB)
{
e.Row.BackColor = Color.White;
}

else 
{
e.Row.BackColor = Color.Red;
}
}
}

As a result, all the incorrect input will become red-highlighted.
Now, I would like to delete all incorrect input in text box but I have no idea how to do it.

if i add in these 2,

string error = tileInput;
TextBoxTileID.Text = tileInput.Replace(error, "");

whole input in text box is replaced by empty space.

So is it possible to assign "e.Row.BackColor = Color.Red" to a variable or boolean so that I can detect that this cell is red-colored, so that I can replace the incorrect input with space in text box?

Your help is much appreciated. Thank you!