Difference between revisions of "ROUTINE %DT"

Revision as of 15:13, 9 December 2019

As most of us know, the VA KERNEL has a program %DT which originally came from VA FileMan, which David Whitten assumes was originally written by George Timson.

In that code, there is a line that validates the number of days entered versus the maximum number of daysper month.  The code looks like this:
I %I(2)>28,$E("303232332323",%I(1))+28<%I(2),%I(1)-2!(%I(2)-29)!(%I(3)#4)!('(%I(3)#100)&(%I(3)+1700#400)) G 1 

The local variable % is an array that has the input to this routine.
% has subscripts for the various parts of the date being validated.
%(1) has the {number entered for the month}
%(2) has the {number entered for the day in the month}
%(3) has the {year entered for the date}.

Expanded, this means

IF {the number entered for the day in the month} is greater than 28

AND

TEST

SELECT { the number entered for the month}VALUES

CASE 1 : RETURN (3) ;;January

CASE 2 : RETURN (0) ;;February

CASE 3 : RETURN (3) ;;March

CASE 4 : RETURN (1) ;;April

CASE 5 : RETURN (3) ;;May

CASE 6 : RETURN (2) ;;June

CASE 7 : RETURN (3) ;;July

CASE 8 : RETURN (3) ;;August

CASE 9 : RETURN (2) ;;September

CASE 10 : RETURN (3) ;;October

CASE 11 : RETURN (2) ;;November

CASE 12 : RETURN (3) ;;December

DEFAULT : RETURN (0) ;; invalid month number

END SELECT

ADD SELECT RETURN TO 28 THEN COMPARE LESS THAN {number entered for the day in the month}

AND

TEST {number entered for the month} NUMERICALLY NOT EQUAL TO 2  ;;February

OR {number entered for the day in the month} NUMERICALLY NOT EQUAL TO 29

OR TEST

BOTH

{year entered for the date} MODULO 4  ;; true if 1,2,3

AND

{year entered for the date} MODULO 100 NUMERICALLY EQUALS 0

AND ADD {year entered for the date} TO 1700 THEN MODULO 400 NUMERICALLY NOT EQUALS 0)

GOTO 1 ;; because local variable % is an acceptable date