KeyDown event - how to easily know if the key pressed is numeric?

Question

I am currently handling the KeyDown event of a DataGridView control. One of the columns is filled by calculated values and I want the user to be able to override the cell value if they want.

When the user presses a numeric key, the cell goes into EditMode and allows the user to override the value. If the key is not numeric, nothing happens...

That is working pretty well... the problem is that I find the code for it ugly... I can't seem to find a neat way to handle all the numeric keys in a single condition, so I've made a switch case construct to deal with all the possible numeric keys, like this:

                switch (e.KeyCode)
                {
                    case Keys.D0:
                    case Keys.D1:
                    case Keys.D2:
                    case Keys.D3:
                    case Keys.D4:
                    case Keys.D5:
                    case Keys.D6:
                    case Keys.D7:
                    case Keys.D8:
                    case Keys.D9:
                    case Keys.Decimal:
                    case Keys.NumPad0:
                    case Keys.NumPad1:
                    case Keys.NumPad2:
                    case Keys.NumPad3:
                    case Keys.NumPad4:
                    case Keys.NumPad5:
                    case Keys.NumPad6:
                    case Keys.NumPad7:
                    case Keys.NumPad8:
                    case Keys.NumPad9:

                         [code to make the cell go to editMode, etc...]

Sure, it works, but there has to be a better and shorter way, right?

All I could find using Google is converting e.KeyCode to a char, but when using numeric keys, it goes gives letters even for the numeric values...

Thanks.

Answer 1

If you use the KeyPress event, the event signature has a KeyPressEventArgs with a KeyChar member that gives you the character for the numberpad keys. You can do a TryParse on that to figure out if its a number or not.

private void Form1_KeyPress(object sender, KeyPressEventArgs e)
{
    int i;
    if (int.TryParse(e.KeyChar.ToString(), out i))
    {
        MessageBox.Show("Number");
    }
}

Answer 2

On the msdn help page they use this code in their example:

// Determine whether the keystroke is a number from the top of the keyboard.
if (e.KeyCode < Keys.D0 || e.KeyCode > Keys.D9)

...

// Determine whether the keystroke is a number from the keypad.
if (e.KeyCode < Keys.NumPad0 || e.KeyCode > Keys.NumPad9)