.net(c#) winform文本框只能输入数字,不能其他非法字符

private void textBox3_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
{
    //阻止从键盘输入键
    e.Handled = true;
    if(e.KeyChar>='0' && e.KeyChar <='9')
    {
        e.Handled = false;
    }

}
或者
private void tbID_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (!((e.KeyChar >= '0' && e.KeyChar <= '9') || e.KeyChar == ' '))//不输入输入除了数字之外的所有非法字符的判断
            {
                e.Handled = true;
            }
        }


多条件的：

private void TxtUser_KeyPress(object sender, KeyPressEventArgs e)
        {
            //阻止从键盘输入键
           e.Handled = true;

            if ((e.KeyChar >= '0' && e.KeyChar <= '9') || (e.KeyChar == (char)8))
            {

                if ((e.KeyChar == (char)8)) { e.Handled = false; return; }
                else
                {
                    int len = TxtUser.Text.Length;
                    if (len < 5)
                    {
                        if (len == 0 && e.KeyChar != '0')
                        {
                            e.Handled = false; return;
                        }
                        else if(len == 0)
                        {
                            MessageBox.Show("编号不能以0开头！"); return;
                        }
                        e.Handled = false; return;
                    }
                    else
                    {
                        MessageBox.Show("编号最多只能输入5位数字！");
                    }
                }
            }
            else
            {
                MessageBox.Show("编号只能输入数字！");
            }
           

        }