For Loop will not Create New Textboxes in a C# Windows Forms Application

Question

I was intending to have this create as many textboxes as the value of numericUpDown1, and I'm going to make some tweaks so that it also deletes textboxes when the value is lowered, but it is not functioning at all. I'm not really sure why this is happening.

private void numericUpDown1_ValueChanged(object sender, EventArgs e)
{
      var numVal = numericUpDown1.Value;

      int count = 2;
      int y = 86;
            
      for (int i = 0; i < numVal; i++)
      {
            //Create the dynamic TextBox.
            TextBox text1 = new TextBox();
            y += 20;
            text1.Location = new Point(719, y);
            text1.Name = "gearText_" + count;
            count += 1;
      }
}

Probably because you're not adding the new TextBox Controls to any container, so they're in a limbo. -- I suggest to use a FlowLayoutPanel as container and a backing collection, as a Dictionary<int, TextBox>. -- Note that, to remove a Control, you must dispose of it. To add it, you should add one or more to a collection, but not repeat the same loop each time the counter is increased (thus, you should probably store the previous value and use the difference). — Jimi
– Jimi, Commented Jul 14, 2021 at 1:51

Thomson Mixab · Accepted Answer · 2021-07-14 01:51:43Z

2

You need to add the textbox control to the form for it to show up.

private void numericUpDown1_ValueChanged(object sender, EventArgs e)
{
      var numVal = numericUpDown1.Value;

      int count = 2;
      int y = 86;
            
      for (int i = 0; i < numVal; i++)
      {
            //Create the dynamic TextBox.
            TextBox text1 = new TextBox();
            y += 20;
            text1.Location = new Point(719, y);
            text1.Name = "gearText_" + count;
            count += 1;
            Form1.Controls.Add(text1);
      }
      Form1.Show();
}

answered Jul 14, 2021 at 1:51

Thomson Mixab

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Comments

shadowraz · Accepted Answer · 2021-07-14 04:10:12Z

You cand do something like this:

public partial class Form1 : Form
{
    private int y = 50;
    public Form1()
    {
        InitializeComponent();
    }

    private void numericUpDown1_ValueChanged(object sender, EventArgs e)
    {
        decimal nudValue = numericUpDown1.Value;

        TextBox tb = new TextBox();

        tb.Location = new Point(50, y += 50);
        tb.Text = "Testbutton";

        this.Controls.Add(tb);
    }
}

But with that cycle you are doing, you are going to add more textboxes than the specified in the Numeric UpDown, if you click it the first time it will be 1, so the code will add one text box, the next time it will add 2 to the existing one, making them 3 when the Numeric UpDwon is 2, and so on ...

In order to delete them when the numeric updown value is decreased you need a reference to those textboxes from the Form.Controls property.

user16317554 · Accepted Answer · 2021-07-14 12:14:59Z

0

Try this:

private void numericUpDown1_ValueChanged(object sender, EventArgs e)
    {
        var numVal = numericUpDown1.Value;

        int count = 2;
        int y = 86;

        for (int i = 0; i < numVal; i++)
        {
            //Create the dynamic TextBox.
            TextBox text1 = new TextBox();
            y += 20;
            text1.Location = new Point(719, y);
            text1.Name = "gearText_" + count;
            count += 1;

            this.Controls.Add(text1);
        }
    }

answered Jul 14, 2021 at 12:14

user16317554

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