I am performing a calculation inside a FormView Insert Template using Visual Studio 2005 and C#. The calculation works fint until a TextBox is left empty. Then I get an expected error message;

Input string was not in a correct format.

There are 100 TextBoxes on this form at which any 80% can be left blank. This is acceptable.

The TextBoxes are databound and if I change the text in the properties, I lose the databind.

This is where I need help;
I need to populate the TextBoxes with a value if the user has not so the calculation can continue.

Here is my code so far;

protected void Button1_Click(object sender, EventArgs e)
        string num1 = ((TextBox)FormView1.FindControl("num1TextBox")).Text;
        string num2 = ((TextBox)FormView1.FindControl("num2TextBox")).Text;
         string num3 = ((TextBox)FormView1.FindControl("num3TextBox")).Text;
        double total;
        total = double.Parse(num1) + double.Parse(num2) + double.Parse(num3);
        ((TextBox)FormView1.FindControl("totalTextBox")).Text = total.ToString();


Again if all boxes are filled it works fine.


if the texbox was bound to the database and there is no value then num1 num2 etc. is empty or null, neither of which will parse to a double to be able to be added. You need to do a test to see if they are null or empty and make thier value 0.
The easiest way is to set the value to 0 when you pull it from the database (either set the value to 0 or put 0 in its place in the stored proc). Or you can do it just before you do your sum.

The text boxes are null from the database, I programmed a solution, while a little backwards, with so many textboxes to fill out it seemed silly to have the client do it.

I simply created a populate/clear button and with the click of a single button all the text boxes were filled with a "0". The client can fill out what textboxes are necessary and then calculate.

protected void Button2_Click(object sender, EventArgs e)
        //Clear Hours and prepopulate with "0"
        ((TextBox)FormView1.FindControl("num1TextBox")).Text = "0";
        ((TextBox)FormView1.FindControl("num2TextBox")).Text = "0";
        ((TextBox)FormView1.FindControl("num3TextBox")).Text = "0";


Hope this helps.