Question

In my windows phone7(silverlight) application I have to restrict inserting symbols for a textbox. Basically I need only to allow inserting alphanumeric characters.

So as the first step I added

InputScope="AlphanumericHalfWidth" and then InputScope="AlphanumericFullWidth".

But in both the situations, the keyboard shows and allows to enter the following characters and many more. @ # $ % & % ( ) !

Therefore I just implemented the following logic in the text box KeyDown event

    if (!( (e.PlatformKeyCode >= 48 && e.PlatformKeyCode <= 57) || (e.PlatformKeyCode >= 65 && e.PlatformKeyCode <= 90) || (e.PlatformKeyCode >= 97 && e.PlatformKeyCode <= 122)))
    {
         e.Handled = true;
    }

But the thing is It still allows to enter the following characters for the textbox. @ # $ % & % ( ) !

Can’t figure out how exactly I have to achieve this. If someone can guide me a way to restrict all the other characters except alphanumeric to be inserted for the textbox, would really appreciate. Thanks….

Answer 1

This is because PlatformKeyCode are not ASCII values, which you are trying to handle.

Use TextChanged event handler:

private void bla_TextChanged(object sender, TextChangedEventArgs e)
{
    bla.Text = Regex.Replace(bla.Text, @"[^\w\s]", string.Empty);
}

where bla is the textbox name.