Restrict textbox to accept numbers and letters only in Windows 8 store app

Question

I am new in programming and I'm trying to make a textbox which only accepts letters and numbers. I've searched for solutions but I can't find exactly what I want. This is what I've done so far:

private void TB1_KeyDown(object sender, KeyRoutedEventArgs e)
    {
        if (e.Key == VirtualKey.Space)
        {
            e.Handled = true;
        }
        var regex = new Regex(@"[^a-zA-Z0-9\s]");
        if (regex.IsMatch(e.Key.ToString()))
        {
            e.Handled = true;
        }
    }

I can remove numbers to regex to prevent the user on typing special characters but this will also restrict them in typing numbers. This textbox will be a part of windows 8 store app and I am using C#. Hope somebody can help me. Thanks!

EDIT:

I have to give up restricting user to type special characters in the text box 'coz I'm not getting any closer to it. What I did is I used my first code but with some changes.

private void TB1_KeyDown(object sender, KeyRoutedEventArgs e)
    {
        if (e.Key == VirtualKey.Enter)
        {
            var regex = new Regex(@"[^a-zA-Z0-9\s]");
            if (regex.IsMatch(TB1.Text))
            {
                t1.Text = "Can't contain special characters.";
            }
        }

    }

Instead of using the keypressed in testing in "IsMatch" I used the text in the textbox. This if statement will filter if other characters aside from numbers and letters are present on the textbox so I created a textblock that will comment that there's a special character in the textbox.

Answer 1

In case you want to use Regex , Use following regex expression to match with.

^[a-zA-Z0-9]*$

Example use:

Regex r = new Regex("^[a-zA-Z0-9]*$");
if (r.IsMatch(SomeString))
{
      ...
}

Answer 2

My previous answer were incorrect because I made a mistake in how the VirtualKey works (it is not a char value).

Virtual keys has a defined value for any number that is 0 -9 and lower case A (a) and upper case A (A) has the same number so I am sorry if I led you in the wrong direction at first.

if(e.Key >= VirtualKey.Number0 && e.Key <= VirtualKey.Z) e.Handled = false;

This code should check that your key value is above or equal to the value for Number0 (48) and below or equal to Z | z (90).

You can read more about VirtualKey here

Answer 3

Enter following line in your KayPress event of textbox. It will not allow user to enter any alphabate or any digit. Only symbols will be allowed to enter:

 e.Handled = char.IsLetter(e.KeyChar) || char.IsDigit(e.KeyChar) ? false:true;

sample code:

        private void yourTextBoxName_KeyPress(object sender, KeyPressEventArgs e)
        {
            e.Handled = char.IsLetter(e.KeyChar) || char.IsDigit(e.KeyChar) ?false:true;
        }