Winform's TextBox input date format validates yyyy mm dd

private void button1_Click(object sender, EventArgs e)
        {
            string s = textBox1.Text.ToString();
            bool b = ValidateDataTime(s);
            string rs = "";
            if (b)
            {
                rs = "true";
            }
            else
            {
                rs = "false";
            }
            MessageBox.Show(rs);
        }
        // Validation method - Format for: YYYY-MM-DD
        public static bool ValidateDataTime(string InputStr) 
        {
            if (InputStr.Length >0) 
            { 
                if(Regex.IsMatch(InputStr.Trim(),@"^((((1[6-9]|[2-9]\d)\d{2})-(0?[13578]|1[02])-(0?[1-9]|[12]\d|3[01]))|(((1[6-9]|[2-9]\d)\d{2})-(0?[13456789]|1[012])-(0?[1-9]|[12]\d|30))|(((1[6-9]|[2-9]\d)\d{2})-0?2-(0?[1-9]|1\d|2[0-8]))|(((1[6-9]|[2-9]\d)(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00))-0?2-29-))$")) 
                {
                    return true; 
                }
                else 
                {
                    return false; 
                }

            }
            return false; 
        } 

YYYY-MM-DD basically takes into account leap years, February, and so on
^((((1[6-9]|[2-9]\d)\d{2})-(0?[13578]|1[02])-(0?[1-9]|[12]\d|3[01]))|(((1[6-9]|[2-9]\d)\d{2})-(0?[13456789]|1[012])-(0?[1-9]|[12]\d|30))|(((1[6-9]|[2-9]\d)\d{2})-0?2-(0?[1-9]|1\d|2[0-8]))|(((1[6-9]|[2-9]\d)(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00))-0?2-29-))$    

Below is the time-verified    

^((((1[6-9]|[2-9]\d)\d{2})-(0?[13578]|1[02])-(0?[1-9]|[12]\d|3[01]))|(((1[6-9]|[2-9]\d)\d{2})-(0?[13456789]|1[012])-(0?[1-9]|[12]\d|30))|(((1[6-9]|[2-9]\d)\d{2})-0?2-(0?[1-9]|1\d|2[0-8]))|(((1[6-9]|[2-9]\d)(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00))-0?2-29-))     (20|21|22|23|[0-1]?\d):[0-5]?\d:[0-5]?\d$