Question

I have two form (Form1,form2)
this code on form2 …
I make a loop of all controls on form1 and get name of the control (ControlName)
I want send any text (ex.”sherif”) to this control (case button)

 foreach (Control ctrl in form1.Controls)
{
    form1.Controls[ControlName]).Text = "sherif";
}

error message appears
NullReferenceException
Object reference not set to an instance of an object.
if the pointer stop above [ControlName] read name of control, but when continue
Comes an Null value

Answer 1

If you just want to change the Text properties of all controls in a form, this should do it:

foreach (Control ctrl in form1.Controls)
{
   ctrl.Text = "sherif";
}

Note this will only change the controls in the top level and not nested controls….

If you need this for nested controls too, do it recursively:

 public void RecursiveChange(Control control)       
 {

    foreach (Control ctrl in control.Controls)
    {
       RecursiveChange(ctrl);
       ctrl.Text = "sherif";
    }
 }