[c#] Foreach Control in form, how can I do something to all the TextBoxes in my Form?

How can I use a Foreach Statement to do something to my TextBoxes?

foreach (Control X in this.Controls)
{
    Check if the controls is a TextBox, if it is delete it's .Text letters.
}

Just add other control types:

public static void ClearControls(Control c)
{

    foreach (Control Ctrl in c.Controls)
    {
        //Console.WriteLine(Ctrl.GetType().ToString());
        //MessageBox.Show ( (Ctrl.GetType().ToString())) ;
        switch (Ctrl.GetType().ToString())

        {
            case "System.Windows.Forms.CheckBox":
                ((CheckBox)Ctrl).Checked = false;
                break;

            case "System.Windows.Forms.TextBox":
                ((TextBox)Ctrl).Text = "";
                break;

            case "System.Windows.Forms.RichTextBox":
                ((RichTextBox)Ctrl).Text = "";
                break;

            case "System.Windows.Forms.ComboBox":
                ((ComboBox)Ctrl).SelectedIndex = -1;
                ((ComboBox)Ctrl).SelectedIndex = -1;
                break;

            case "System.Windows.Forms.MaskedTextBox":

                ((MaskedTextBox)Ctrl).Text = "";
                break;

            case "Infragistics.Win.UltraWinMaskedEdit.UltraMaskedEdit":
                ((UltraMaskedEdit)Ctrl).Text = "";
                break;

            case "Infragistics.Win.UltraWinEditors.UltraDateTimeEditor":
                DateTime dt = DateTime.Now;
                string shortDate = dt.ToShortDateString();
                ((UltraDateTimeEditor)Ctrl).Text = shortDate;
                break;

            case "System.Windows.Forms.RichTextBox":
                ((RichTextBox)Ctrl).Text = "";
                break;


            case " Infragistics.Win.UltraWinGrid.UltraCombo":
                ((UltraCombo)Ctrl).Text = "";
                break;

            case "Infragistics.Win.UltraWinEditors.UltraCurrencyEditor":
                ((UltraCurrencyEditor)Ctrl).Value = 0.0m;
                break;

            default:
                if (Ctrl.Controls.Count > 0)
                    ClearControls(Ctrl);
                break;

        }

    }
}

foreach (Control X in this.Controls)
{
  if (X is TextBox)
  {
    (X as TextBox).Text = string.Empty;
  }
}

Also you can use LINQ. For example for clear Textbox text do something like:

this.Controls.OfType<TextBox>().ToList().ForEach(t => t.Text = string.Empty);

The trick here is that Controls is not a List<> or IEnumerable but a ControlCollection.

I recommend using an extension of Control that will return something more..queriyable ;)

public static IEnumerable<Control> All(this ControlCollection controls)
    {
        foreach (Control control in controls)
        {
            foreach (Control grandChild in control.Controls.All())
                yield return grandChild;

            yield return control;
        }
    }

Then you can do :

foreach(var textbox in this.Controls.All().OfType<TextBox>)
{
    // Apply logic to the textbox here
}

Check this:

foreach (Control x in this.Controls)
{
    if (x is TextBox)
    {
        x.Text = "";
    }
}

If you are using C# 3.0 or higher you can do the following

foreach ( TextBox tb in this.Controls.OfType<TextBox>()) {
  ..
}

Without C# 3.0 you can do the following

foreach ( Control c in this.Controls ) {
  TextBox tb = c as TextBox;
  if ( null != tb ) {
    ...
  }
}

Or even better, write OfType in C# 2.0.

public static IEnumerable<T> OfType<T>(IEnumerable e) where T : class { 
  foreach ( object cur in e ) {
    T val = cur as T;
    if ( val != null ) {
      yield return val;
    }
  }
}

foreach ( TextBox tb in OfType<TextBox>(this.Controls)) {
  ..
}

A lot of the above work. Just to add. If your textboxes are not directly on the form but are on other container objects like a GroupBox, you will have to get the GroupBox object and then iterate through the GroupBox to access the textboxes contained therein.

foreach(Control t in this.Controls.OfType<GroupBox>())
{
   foreach (Control tt in t.Controls.OfType<TextBox>())
   {
        // do stuff
   }
}

You can do the following:

foreach (Control X in this.Controls)
{
    TextBox tb = X as TextBox;
    if (tb != null)
    {
        string text = tb.Text;
        // Do something to text...
        tb.Text = string.Empty; // Clears it out...
    }
}

Even better, you can encapsule this to clear any type of controls you want in one method, like this:

public static void EstadoControles<T>(object control, bool estado, bool limpiar = false) where T : Control
        {
            foreach (var textEdits in ((T)control).Controls.OfType<TextEdit>()) textEdits.Enabled = estado;
            foreach (var textLookUpEdits in ((T)control).Controls.OfType<LookUpEdit>()) textLookUpEdits.Enabled = estado;

            if (!limpiar) return;
            {
                foreach (var textEdits in ((T)control).Controls.OfType<TextEdit>()) textEdits.Text = string.Empty;
                foreach (var textLookUpEdits in ((T)control).Controls.OfType<LookUpEdit>()) textLookUpEdits.EditValue = @"-1";
            }
        }

simple using linq, change as you see fit for whatever control your dealing with.

        private void DisableButtons()
    {
        foreach (var ctl in Controls.OfType<Button>())
        {
            ctl.Enabled = false;
        }
    }

    private void EnableButtons()
    {
        foreach (var ctl in Controls.OfType<Button>())
        {
            ctl.Enabled = true;
        }
    }

private IEnumerable<TextBox> GetTextBoxes(Control control)
{
    if (control is TextBox textBox)
    {
        yield return textBox;
    }

    if (control.HasChildren)
    {
        foreach (Control ctr in control.Controls)
        {
            foreach (var textbox in GetTextBoxes(ctr))
            {
                yield return textbox;
            }
        }
    }
}

I found this to work very well, but initially I have my textboxes on a panel so none of my textboxes cleared as expected so I added

this.panel1.Controls.....  

Which got me to thinking that is you have lots of textboxes for different functions and only some need to be cleared out, perhaps using the multiple panel hierarchies you can target just a few and not all.

foreach ( TextBox tb in this.Controls.OfType<TextBox>()) {
  ..
}

foreach (Control x in this.Controls)
{
  if (x is TextBox)
  {
    ((TextBox)x).Text = String.Empty;
//instead of above line we can use 
     ***  x.resetText();
  }
}