[C#] - WinForm TextBox 유효한 숫자만 입력받게 하기

MSDN KeyDown Event

https://msdn.microsoft.com/ko-kr/library/system.windows.forms.control.keydown(v=vs.110).aspx

 

Ctrl + V 를 통한 입력은 방지 하였습니다.

private void InputTextBox_KeyDown(object sender, KeyEventArgs e)
{
        TextBox textBox = sender as TextBox;

        if (e.Control && e.KeyCode == Keys.V)
        {
                e.SuppressKeyPress = true;
                return;
        }

        bool numberEntered = false;
        if (e.KeyCode >= Keys.D0 && e.KeyCode <= Keys.D9)
        {
                numberEntered = true;
        }
        else if (e.KeyCode >= Keys.NumPad0 && e.KeyCode <= Keys.NumPad9)
        {
                numberEntered = true;
        }

        if (numberEntered)
        {
                if (textBox.Text.Length == 0)
                {
                        if (e.KeyValue == '0')
                        {
                                e.SuppressKeyPress = true;
                        }
                }
                else
                {
                        if (textBox.Text.ElementAt(0) != '0')
                        {
                                int selectionStart = textBox.SelectionStart;
                                if ((selectionStart == 0) && (e.KeyValue == '0'))
                                {
                                    e.SuppressKeyPress = true;
                                }
                        }
                }
        }
}

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