How to validate textbox to accept only numeric values in c# windown application ?

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C#

private void txtPrinterNumber_KeyPress(object sender, KeyPressEventArgs e)
       {
           if (!System.Text.RegularExpressions.Regex.IsMatch(e.KeyChar.ToString(), "\\d+"))
               e.Handled = true;

       }

Posted 16-Feb-15 23:50pm

Dev Chandra Thakur

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BillWoodruff 17-Feb-15 5:55am

There's numbers, and then there's ... numbers. Filtering for integers is one thing, filtering for Doubles is another. How many decimal-points/period/dots do you allow if you're filtering for a Double ... and where; what if the current culture defines a comma as a valid separator in a number as in 100,000.9345 ?

What did you have in mind ? Specifics, please.

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RajeeshMenoth · Answer 1 · 2015-02-16T23:56:00

C#

private void txtPrinterNumber_KeyPress(object sender, KeyPressEventArgs e)
{
    if (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar) &&
        (e.KeyChar != '.'))
    {
            e.Handled = true;
    }

    // only allow one decimal point
    if ((e.KeyChar == '.') && ((sender as TextBox).Text.IndexOf('.') > -1))
    {
        e.Handled = true;
    }
}

OriginalGriff · Answer 2 · 2015-02-16T23:59:00

It can be done - it's not complex, it's just annoying, because you have to handle it in a number of places to prevent paste adding alpha as well.

The better solution is to use a NumericUpDown control, which does it all for you.

If you are going to do it manually, consider looking at the TextChanged event and using Regex.Replace instead of IsMatch - but don't forget the cursor position may need correcting.

How to validate textbox to accept only numeric values in c# windown application ?

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