SIGN Function

[StephenG1CMZ]

(01-04-2017 12:19 PM)ggauny@live.fr Wrote:  It is always the same result : Date OK

if I write 23 2 1935
or 0 2 1935
or 23 0 1935
or 23 2 0

I obtain "Date OK" !!!

I was wanted a sort cut, but ...

To explain why it is not working: your program logic is not correct.
These examples all yield the same answer:

Sign of 23 2 95 is 1 or 1 or 1 which is 1==0
Sign of. 0 2 95 is 0 or 1 or 1 which is 1
Sign of 23 0 95 is 1 or 0 or 1 which is 1
Sign of 23 2 0 is 1 or 1 or 0 which is 1

Sign of 0 0 0 is 0 or 0 or 0 which is 0==0 (the only time your date is not ok)

The sign generates 0 if the input is 0
The Or generates 0 only if every input is 0, otherwise its 1.

To check if J A M are all nonzero you could use
If J AND A AND M // Prime treats 0 as false
THEN PRINT("Date maybe ok"); //All three nonzero
// dont forget many other invalid dates exist, eg 33 3 95
ELSE PRINT("At least one 0");
END;//IF

Hope that makes it clearer