C#

for (int i = 0; i < m_panels.Length; i++)
{
  if (m_panels[i] != null)
  {
     panel1.Controls.Remove(m_panels[i]);
     m_panels[i].Dispose();
     m_panels[i] = null;
  }
}

// in Form scope
List<Panel> m_panels = new List<Panel>();

// in the method you call to create a new Panel
Panel newPanel = new Panel();

newPanel.Name = "panel m_" + i.ToString();
newPanel.BackColor = Color.Red;
newPanel.Location = e.Location; // doing this on mouse click event
newPanel.Size = new System.Drawing.Size(12, 12);
newPanel.Visible = true;

m_panels.Add(newPanel);
panel1.Controls.Add(newPanel);

// to force an error in testing add this:
// m_panels.Add(new Panel { Name = "make an error" });

// in the method you call to clear the current Panels
for (int i = 0; i < m_panels.Count; i++)
{
    Panel panelToRemove = m_panels[i];

    // being paranoid is good !
    if (panel1.Controls.Contains(panelToRemove))
    {
        panel1.Controls.Remove(panelToRemove);
    }
    else
    {
        throw new MissingMemberException(
            string.Format("Panel: {0} in source list of Panels not in panel1.Controls", 
            panelToRemove.Name));
    }
}

// clear the List for re-use
m_panels.Clear()

/// <summary>
/// WPF convert System.Drawing.Image to System.Windows.Media.Imaging.BitmapImage
/// </summary>
/// <param name="img">Image to convert</param>
/// <returns>Converted image</returns>
public static System.Windows.Media.Imaging.BitmapImage ImageToBitmapImage(System.Drawing.Image img)
{
    System.Windows.Media.Imaging.BitmapImage bitmap = new System.Windows.Media.Imaging.BitmapImage();
    using (System.IO.MemoryStream ms = new System.IO.MemoryStream())
    {
        img.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
        ms.Position = 0;
        bitmap.BeginInit();
        bitmap.CacheOption = System.Windows.Media.Imaging.BitmapCacheOption.OnLoad;
        bitmap.StreamSource = ms;
        bitmap.EndInit();
    }
    return bitmap;
}

txtDOB.Text = dr["dob"].ToString("d");

Member 11264479 wrote:

SqlCommand cmd = new SqlCommand("Select * from ApplicantForm Where ApplicantId=" + ((Request.QueryString["ApplicantId"])) + "", con);

using (SqlCommand cmd = new SqlCommand("SELECT dob FROM ApplicantForm WHERE ApplicantId = @ApplicantId", con))
{
    cmd.Parameters.AddWithValue("@ApplicantId", Request.QueryString["ApplicantId"]);
    
    object dob = cmd.ExecuteScalar();
    if (dob != null && !Convert.IsDBNull(dob))
    {
        txtDOB.Text = string.Format("{0:d}", dob);
    }
}

private void button1_Click(object sender, EventArgs e) {
    Thread th = new Thread(run);
    th.Start();
    run();
}
public void run() {
    for (int i = 0; i < 2; i++) {
        UpdateTextBox("I is now " + i);
        Thread.Sleep(100);
    }
}

private delegate void DUpdateTextBox(string text);
private void UpdateTextBox(string text) {
    if (textBox1.InvokeRequired) {
        var d = new DUpdateTextBox(UpdateTextBox);
        textBox1.Invoke(d, text);
    } else {
        textBox1.Text = text;
    }
}

den2k88 wrote:

Thread is the name of the class, not of the instance.

Bastard Programmer from Hell
If you can't read my code, try converting it here[^]

// as already mentioned in the other replies there are issues when trying to access a textbox or any
// other ui object (in forms). So the invoke is needed to be called, but let me give you a quick tip 
// here: Threads are pretty performance related. Microsoft does give you the ability of using tasks. 
// They are easy to use and pretty similar to the threading system. So try to use your code like this 
// for example:

// (you can decrease the code you've written to just a few lines)
// just navigate to your custom form type constructor:
public FormType() {
     button.Cick += (o, e) => {
          Task.Factory.StartNew(() => {
               for (var i = 0; i < 2; i++) {
                    // if you are always using the invoke method it will still work. There's no need to use
                    // the 'InvokeRequired' property before 
                    textBox.Invoke((Action)delegate { 
                         textBox.Text = string.Format("Variable i currently set to: {0}", i); 
                    });
                    // you are still inside a thread
                    Thread.Sleep(100);
               }
          });
     }
}

// Hope that this gives you some kind of help. Looks like you're just starting with threads and
// background working stuff. If so try to use learn the task thing instead ;) Greetz