C#设置textBox只能输入数字（正数，负数，小数）简单实现

*设置textBox只能输入数字（正数，负数，小数）
       */
        public static bool NumberDotTextbox_KeyPress(object sender, KeyPressEventArgs e)
        {
            //允许输入数字、小数点、删除键和负号
            if ((e.KeyChar < 48 || e.KeyChar > 57) && e.KeyChar != 8 && e.KeyChar != (char)('.') && e.KeyChar != (char)('-'))
            {
                return true;
            }
            if (e.KeyChar == (char)('-'))
            {
                if ((sender as TextBox).Text != "")
                {
                    return true;
                }
            }
            //小数点只能输入一次
            if (e.KeyChar == (char)('.') && ((TextBox)sender).Text.IndexOf('.') != -1)
            {
                return true;
            }
            //第一位不能为小数点
            if (e.KeyChar == (char)('.') && ((TextBox)sender).Text == "")
            {
                return true;
            }
            //第一位是0，第二位必须为小数点
            if (e.KeyChar != (char)('.') && e.KeyChar != 8 && ((TextBox)sender).Text == "0")
            {
                return true;
            }
            //第一位是负号，第二位不能为小数点
            if (((TextBox)sender).Text == "-" && e.KeyChar == (char)('.'))
            {
                return true;
            }
 
            return false;
        }
 
        public static bool NumberTextbox_KeyPress(KeyPressEventArgs e)
        {
            if (e.KeyChar != '')//这是允许输入退格键
            {
                if ((e.KeyChar < '0') || (e.KeyChar > '9'))//这是允许输入0-9数字
                {
                    return true;
                }
            }
 
            return false;
        }