neoHOW7: Check if a date is valid

Following up on Check if a particular year is a LEAP year, here is a routine to check if a date is valid. By definition, a date is valid if all of theese conditions are true ...

a) The year is an integer greater than or equal to 0
b) The month is an integer between 1 and 12
c) For months 1, 3, 5, 7, 8, 10 and 12, the day is an integer between 1 and 31
d) For months 4, 6, 9 and 11, the day is an integer between 1 and 30
e) For month 2, the day is an integer between 1 and 29 (Leap Years) or 28 (otherwise)

You deploy this subroutine (IsThisAValidDate) by supplying the value to be checked in variable [IsThisAValidDate/Input] ... and upon return, examine the contents of [IsThisAValidDate/Answer] ... the contents of which will be "True" or a description of the error encountered.

Here is an example code snippet ...

... assume date to be validated was entered in [TextEntry1] SetVar "[IsThisAValidDate/Input]" "![DateEntered]" SetVar "[IsThisAValidDate/Format]" "!/mdy" GoSub "IsThisAValidDate" If "[IsThisAValidDate/Answer]" "=" "True" AlertBox "OK" "[TextEntry1] is a valid Date" Else AlertBox "Error ..." "[IsThisAValidDate/Answer]" EndIf

And here is the subroutine you would paste in your pub's SubRoutines section ...

:IsThisAValidDate ... examines [IsThisAValidDate/Input], [IsThisAValidDate/Format] ... returns True/False in [IsThisAValidDate/Answer] ... split into day, month and year SubStr "[IsThisAValidDate/Format]" "1" "1" "[IsThisAValidDate/Format1]" StrParse "[IsThisAValidDate/Input]" "[IsThisAValidDate/Format1]" "[IsThisAValidDate/Part]" "[IsThisAValidDate/Count]" ... got 3 parts ? If "[IsThisAValidDate/Count]" "<>" "3" SetVar "[IsThisAValidDate/Answer]" "!Did not find expected 2 separator characters [IsThisAValidDate/Format1]" Return EndIf ... identify day, month and year parts SubStr "[IsThisAValidDate/Format]" "2" "4" "[IsThisAValidDate/Format234]" If "[IsThisAValidDate/Format234]" "=" "dmy" SetVar "[IsThisAValidDate/Day]" "[IsThisAValidDate/Part1]" SetVar "[IsThisAValidDate/Month]" "[IsThisAValidDate/Part2]" SetVar "[IsThisAValidDate/Year]" "[IsThisAValidDate/Part3]" Endif If "[IsThisAValidDate/Format234]" "=" "mdy" SetVar "[IsThisAValidDate/Month]" "[IsThisAValidDate/Part1]" SetVar "[IsThisAValidDate/Day]" "[IsThisAValidDate/Part2]" SetVar "[IsThisAValidDate/Year]" "[IsThisAValidDate/Part3]" Endif ... other date formats can be added/supported here ... is [IsThisAValidDate/Year] an integer ? Math "[IsThisAValidDate/Year]/1" "0" "[IsThisAValidDate/Y1]" Math "[IsThisAValidDate/Year]-([IsThisAValidDate/Y1]*1)" "-1" "[IsThisAValidDate/Y2]" If "[IsThisAValidDate/Y2]" "<>" "!0" SetVar "[IsThisAValidDate/Answer]" "YearNotInteger" Return EndIf ... is [IsThisAValidDate/Year] less than zero ? If "[IsThisAValidDate/Year]" "<" "!0" SetVar "[IsThisAValidDate/Answer]" "YearIsNegative" Return EndIf ... is [IsThisAValidDate/Month] an integer ? Math "[IsThisAValidDate/Month]/1" "0" "[IsThisAValidDate/M1]" Math "[IsThisAValidDate/Month]-([IsThisAValidDate/M1]*1)" "-1" "[IsThisAValidDate/M2]" If "[IsThisAValidDate/M2]" "<>" "!0" SetVar "[IsThisAValidDate/Answer]" "MonthNotInteger" Return EndIf ... is [IsThisAValidDate/Month] an integer between 1 and 12 If "[IsThisAValidDate/Month]" "<" "1" SetVar "[IsThisAValidDate/Answer]" "MonthLessThan1" Return EndIf If "[IsThisAValidDate/Month]" ">" "12" SetVar "[IsThisAValidDate/Answer]" "MonthGreaterThan12" Return EndIf ... is [IsThisAValidDate/Day] an integer ? Math "[IsThisAValidDate/Day]/1" "0" "[IsThisAValidDate/D1]" Math "[IsThisAValidDate/Day]-([IsThisAValidDate/D1]*1)" "-1" "[IsThisAValidDate/D2]" If "[IsThisAValidDate/D2]" "<>" "!0" SetVar "[IsThisAValidDate/Answer]" "DayNotInteger" Return EndIf ... is [IsThisAValidDate/Day] an integer ? If "[IsThisAValidDate/Day]" "<" "1" SetVar "[IsThisAValidDate/Answer]" "DayLessThan1" Return Endif ... jan, mar, may, jul, aug, oct and dec have 31 days ... for [IsThisAValidDate/Month] 1, 3, 5, 7, 8, 10 or 12 ... is [IsThisAValidDate/Day] an integer between 1 and 31 SetVar "[IsThisAValidDate/MonthsWith31Days]" "$1,$3,$5,$7,$8,$10,$12" SearchStr "$[IsThisAValidDate/Month]" "[IsThisAValidDate/MonthsWith31Days]" "[IsThisAValidDate/SearchPos]" If "[IsThisAValidDate/SearchPos]" ">" "!0" ... yes it is one of the 31 day months If "[IsThisAValidDate/Day]" ">" "31" SetVar "[IsThisAValidDate/Answer]" "DayGreaterThan31" Else SetVar "[IsThisAValidDate/Answer]" "True" Endif Return EndIf ... apr, jun, sep and nov have 30 days ... for [IsThisAValidDate/Month] 4, 6, 9 or 11 ... is [IsThisAValidDate/Day] an integer between 1 and 30 SetVar "[IsThisAValidDate/MonthsWith30Days]" "$4,$6,$9,$11" SearchStr "$[IsThisAValidDate/Month]" "[IsThisAValidDate/MonthsWith30Days]" "[IsThisAValidDate/SearchPos]" If "[IsThisAValidDate/SearchPos]" ">" "!0" ... yes it is one of the 30 day months If "[IsThisAValidDate/Day]" ">" "30" SetVar "[IsThisAValidDate/Answer]" "DayGreaterThan30" Else SetVar "[IsThisAValidDate/Answer]" "True" Endif Return Endif EndIf ... feb (28 or 29 days) ... for [IsThisAValidDate/Month] 2 ... is [IsThisAValidDate/Day] 29 (leap year) or 28 (otherwise) ... go check if it is leap year SetVar "[IsThisALeapYear/Input]" "[IsThisAValidDate/Year]" GoSub "IsThisALeapYear" If "[IsThisALeapYear/Answer]" "=" "True" ... leap year ; day can be 29 or less If "[IsThisAValidDate/Day]" ">" "29" SetVar "[IsThisAValidDate/Answer]" "DayGreaterThan29" Else SetVar "[IsThisAValidDate/Answer]" "True" Endif Return Else ... not a leap year ; day can be 28 or less If "[IsThisAValidDate/Day]" ">" "28" SetVar "[IsThisAValidDate/Answer]" "DayGreaterThan28" Else SetVar "[IsThisAValidDate/Answer]" "True" Endif Return EndIf SetVar "[IsThisAValidDate/Answer]" "True" Return

Of course, if you plan on using such a function in many projects, you might consider turning the subroutine into a NeoBook Function ... something you might Call from any pub in your computer ... for example ...

Call "gkIsThisAValidDate" "[TextEntry1]" "!/dmy" "[Result]"