Looping through tabpages of tabcontrol in c#

Question

I am trying to Loop through the tabpages of a tabcontrol in c#. Each tabpage has multiple textboxes. The purpose is to sum up all of the values of these textboxes.

double sum = 0;
foreach(TabPage tbp in tabControl1.TabPages)
{
    foreach(System.Windows.Forms.Control c in tbp.Controls)
    {
            if (c.ToString() == "TextBox")
            {
                sum += Convert.ToDouble(c.Text);
            }
        }
    }

When I execute this code, the first foreach loop is entered three times even though I have one TabPage in my TabControl. Furthermore, the if statement is not entered, so there seems to be something wrong with that as well.

Answer 1

This code (C#7) allows you to safety sum all text boxes values in a tab control, include text boxes nested in children container controls (example: a text box in panel, and the panel in a tab page)

    private double SumTextBoxesValues()
    {
        double sum = 0;
        foreach (TabPage tbp in tabControl1.TabPages)
        {
            var textBoxes = GetAllTextBoxes(tbp);

            foreach (var textBox in textBoxes)
            {
                if(double.TryParse(textBox.Text, out double value))
                    sum += value;
            }

        }

        return sum;
    }

    private static IEnumerable<TextBox> GetAllTextBoxes(Control container)
    {
        var controlList = new List<TextBox>();
        foreach (Control c in container.Controls)
        {
            controlList.AddRange(GetAllTextBoxes(c));

            if(c is TextBox box)
                controlList.Add(box);
        }
        return controlList;
    }