Re: CVTDAT Question

[Simon Coulter <shc@xxxxxxxxxxxxxxxxx>]

On 30/12/2009, at 11:46 PM, fbocch2595@xxxxxxx wrote:

> My company runs a CL pgm that has been running for many years that  
> reads a date file and converts it to julian but when converting  
> 123110 the pgm is returning CPF0555 due to 123110 being converted   
> to invalid julian date 2010366.  Has anyone seen this type of  
> behavior b4 and how is it best resolved?

Correct interpretation of the error condition might shed some light.  
The error is NOT caused by incorrectly converting 123110 to Julian but  
rather by attempting to convert 2010366 (an invalid Julian date) to  
MDY format.

You should examine the content of &HOLJUL after converting 123110. I  
think you'll find it is 2010365 (the correct value) thus something is  
occurring between that point and the later CVTDAT failure. Usual cause  
is attempting to use Julian dates for "easy" data arithmetic (i.e.,  
adding or subtracting a number of days) and forgetting about the  
boundary conditions of yyyy001 and yyyy365 or yyyy366.

Your code needs to check the validity of the numeric calculation  
pretending to be a date calculation. If you go beyond 1 then decrement  
the year portion and adjust the days. If you go beyond 365 then if 366  
check for leap year and if not a leap or greater than 366 then  
increment the year and adjust the days. You'll need to handle adding  
or subtracting more days than a single year if you want to do it  
properly. Seems to me this is crying out for a user-written command to  
perform the Julian date arithmetic. That way you can hide the  
messiness of the year and day adjustments in a common, reusable, chunk  
of code.

Regards,
Simon Coulter.
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