HP OpenVMS Systems

date math?

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The Question is:

 
How can I add 7 days to a date from within
a Cobol Routine.
Is there a converse of LIB$DAY which converts
number of days to a date.
 
 

The Answer is :

 
  How you do this depends greatly on the original format of the date
  you will be using as a basis for the calculation.  One can see dates
  in various binary formats including quadword and UTC, and one can see
  dates in a variety of text formats.
 
  With text-format dates, you may well be able to use a combination time,
  a text-format time specification that includes both an absolute time and
  a delta time.  In this case, the delta time would be "7-" or similar.
 
  To determine midnight seven days hence (in DCL), use:
 
    $ x = f$cvtim("TODAY+7-","ABSOLUTE")
 
  The lib$add_times call would appear tailor-made to this situation.
  lib$add_times expects one of the two quadwords to be a delta time.
  You will need to call sys$bintim or sys$cvt_[to|from]_internal_time
  to get the quadwords.  To go from binary to text, there are various
  routines including sys$asctim, sys$numtim, lib$cvt_vectim, and
  others.  There are also a variety of UTC-format time routines
  available.
 
  COBOL or other language is only a factor in the relative difficulty of
  calling certain system service routines from the language, and/or in the
  availability of any language-specific date routines.

  

     

     
answer written or last revised on ( 2-OCT-1998 )
     
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