Question

How to hide “all” textboxes together when button is clicked? Is there any short method to avoid hiding them one by one?

gamma_textBox.Visible = false;

Answer 1

foreach(var tb in this.Controls.OfType<TextBox>()) tb.Visible = false;

But note this will not look inside any containers. You can do so recursively though by enumerating each child’s Controls collection. An example of this would be:

public void HideChildTextBoxes(Control parent)
{
    foreach(Control c in parent.Controls)
    {
        HideChildTextBoxes(c);
        if(c is TextBox) c.Visible = false;
    }
}