Allowed only comma in KeyDown C#

Question

I blocked all key on keyboard excluding 1-9 and I have a problem how to enable comma?

My code:

private void textbox_KeyDown(object sender, KeyRoutedEventArgs e)
    if (e.Key >= Windows.System.VirtualKey.Number0 && e.Key <= Windows.System.VirtualKey.Number9 || e.Key >= Windows.System.VirtualKey.NumberPad0 && e.Key <= Windows.System.VirtualKey.NumberPad9 || e.Key == Windows.System.VirtualKey.Decimal)
    {
    e.handled = false;
    }
    else 
    {
    e.handled = true;
    }

Answer 1

This code will allow only numbers and comma

if (!char.IsDigit(e.KeyChar) && e.KeyChar != ',')
{
    e.Handled = true;
}

Alternative

 if ((e.KeyChar > (char)Keys.D9 || e.KeyChar < (char)Keys.D0) && e.KeyChar != ',')
{ 
    e.Handled = true; 
}

Answer 2

try this...

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
        {
            if((e.KeyChar >= 48 && e.KeyChar <= 57) || (e.KeyChar >= 97 && e.KeyChar <= 105))
            {
                e.Handled = true;
            }
            else
            {
                e.Handled = false;
            }
        }

Answer 3

根据虚拟密钥代码的文档，您需要OemComma，它是0xBC或（VirtualKey）188。

Answer 4

You can try this:

        string keyInput = e.KeyChar.ToString();

        if (Char.IsDigit(e.KeyChar))
        {
            // Digits are OK
        }
        else if (e.KeyChar == '\b')
        {
            // Backspace key is OK
        }
        else if (e.KeyChar == ',')
        {
            // Comma key is OK
        }


        else
        {
            // Swallow this invalid key and beep
            e.Handled = true;
            //    MessageBeep();
        }

Answer 5

First of all you have to remember that decimal mark ( either . or , ) has to be set up in the CultureInfo . If you're planning to release your application to the further audience I would recommend keeping this in mind.

Another thing is that your condition makes no sense :

// this has to be always true
e.Key >= Windows.System.VirtualKey.Number0 
&& 
e.Key <= Windows.System.VirtualKey.Number9 
|| // above or below has to be true
e.Key >= Windows.System.VirtualKey.NumberPad0 
&& // something from above has to be true and below has to be true
e.Key <= Windows.System.VirtualKey.NumberPad9 
|| // or just decimal mark .. ?
e.Key == Windows.System.VirtualKey.Decimal

So proceeding with the code :

// check for the keys 
if(
    ( // if numeric between 0 and 9
        e.Key >= Windows.System.VirtualKey.Number0 
        &&
        e.Key <= Windows.System.VirtualKey.Number9
    ) 
    || // or
    ( // numeric from numpad between 0 and 9
        e.Key >= Windows.System.VirtualKey.NumberPad0
        &&
        e.Key <= Windows.System.VirtualKey.NumberPad9 
    )
    || // or decimal mark
    e.Key == Windows.System.VirtualKey.Decimal
)
{
    // your logic
}

Remember that Windows.System.VirtualKey.Decimal will not return the decimal mark ( separator ) based on the CultureInfo but instead the decimal mark from the numpad.

If you want to use culture info ( international application ) you can find decimal mark in CultureInfo.CurrentCulture.NumberFormat.CurrencyDecimalSeparator and then compare the text input.