A simple WinForms numeric edit control

There are plenty of controls out there that will allow only numeric entry but they may not meet your needs. If you don’t want the up/down buttons, the built-in NumericUpDown control won’t be of use and using one of those huge libraries just for their numeric control may be overkill. If that describes your position, this uber-simple control may fit the bill.

  public class NumberControl : TextBox
  {
    /// <summary>
    /// Creates a new <see cref="NumberControl"/> instance.
    /// </summary>
    public NumberControl()
    {
      TextAlign = HorizontalAlignment.Right;
    }

    /// <summary>
    /// Triggered when a key is pressed. Swallows all keys except for digits.
    /// </summary>
    protected override void OnKeyPress(KeyPressEventArgs e)
    {
      base.OnKeyPress(e);
      string decimalSeparator = CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator;
      if (e.KeyChar.ToString() == decimalSeparator)
      {
        if (Text.IndexOf(decimalSeparator) > -1)
          e.Handled = true;
      }
      else if (!char.IsDigit(e.KeyChar) && !char.IsControl(e.KeyChar))
      {
        e.Handled = true;
      }
    }
  }