Question

in WPF It it possible to change a text box’s font size during runtime?

i tried to do that:

foreach (Control ctrl in gridArray[i].Children)
 {
    if(ctrl.GetType() == typeof(TextBox))
    {
        (TextBox)ctrl.FontSize = (double)5;

    }
 }

but it didnt work

Answer 1

The cast does not have a high precedence, your code effectively tries to cast the value in ctrl.FontSize to TextBox, you need to add parenthesis (and the double cast is superfluous):

((TextBox)ctrl).FontSize = 5;

Further the way you check the type of the control is not such a good idea, use is instead. Otherwise sublasses of TextBox are not included.

if (ctrl is TextBox)

Further as you do not only care about the type and cast as well to interact with the TextBox class interface you may as well use as:

var textBox = ctrl as TextBox;
if (textBox != null)
    textBox.FontSize = 5;

This also conveniently gets rid of the parenthesis jungle.