;; | ----------------------------------------------------------------------------
;; | MI_DateFmtOk
;; | ----------------------------------------------------------------------------
;; | Function : Check if date format is Okay
;; | Arguments: dd   - Day portion of the date
;; |            mm   - Month portion of the date
;; |            yyyy - Year portion of the date
;; | Return   : T if format is correct nil otherwise
;; | Updated  : January 20, 1999
;; | Comment  : The correct format for a date is mm/dd/yyyy, in which each of the
;; |            values dd, mm and yyyy must meet criteria for validity including the
;; |            Y2K compliance to 4 digits for year and also the Year 2000 February
;; |            moth of 30 days.
;; |            Checks for leap and 400-multiple years also
;; | e-mail   : rakesh.rao@4d-technologies.com 
;; | Web      : www.4d-technologies.com
;; | ----------------------------------------------------------------------------


(defun MI_DateFmtOk (dd mm yyyy / Ok )
(setq Ok nil)
(if (and
		(and (>= yyyy 1900) (<= yyyy 9999))
		(MI_InBetween mm 1 12)
	)
	(progn
		(cond
			((member mm (list 1 3 5 7 8 10 12))		; 31-day month
				(if (MI_InBetween dd 1 31)
					(setq Ok T)
				)
			)
			((member mm (list 4 6 9 11))			; 30-day month
				(if (MI_InBetween dd 1 30)
					(setq Ok T)
				)
			)
			((= mm 2)								; February
				(cond
					((= (rem yyyy 400) 0)			; Year 2000 kind of leap year (30 days in February)
						(if (MI_InBetween dd 1 30)
							(setq Ok T)
						)
					)
					(T
						(if (= (rem yyyy 4) 0)
						(progn
							(if (MI_InBetween dd 1 29)
								(setq Ok T)
							)
						)
						(progn
							(if (MI_InBetween dd 1 28)
								(setq Ok T)
							)
						))
					)
				)
			)
		)
	)
)
(if Ok
	(strcat (ST_StrZ dd 2) "/" (ST_StrZ mm 2) "/" (itoa yyyy))
	nil
)
)