Date calculation commands for AS/400

As a consultant, over the course of many projects at different places, I periodically would have to calculate certain dates relative to a given date to determine reporting limits (e.g., month end, month begin). I also often had to determine the day of the week. So, I put together a little text file that first contained the calculations for these values. I have since converted the text file to contain procedures so that I can easily create a service program to perform the various date calculations.

h nomain option(*nodebugio:*srcstmt)



     d getPriorMonthEnd...

     d                 pr              d

     d  pDate                          d   const



     d getPriorMonthBegin...

     d                 pr              d

     d  pDate                          d   const



     d getMonthBegin   pr              d

     d  pDate                          d   const



     d getMonthEnd     pr              d

     d  pDate                          d   const



     d getDayOfWeek    pr             1p 0                   Mon = 0 ... Sun = 6

     d  pDate                          d   const



     d isWeekDay       pr              n

     d  pDate                          d   const



     d isWeekEnd       pr              n

     d  pDate                          d   const



     p getPriorMonthEnd...

     p                 b                   export

     d getPriorMonthEnd...

     d                 pi              d

     d  pDate                          d   const

     /free

           return pDate - %days(%subdt(pDate:*days));

      /end-free

     p getPriorMonthEnd...

     p                 e



     p getPriorMonthBegin...

     p                 b                   export

     d getPriorMonthBegin...

     d                 pi              d

     d  pDate                          d   const

      /free

           return getMonthBegin(pDate - %months(1));

      /end-free

 p getPriorMonthBegin...

      p                 e

 

      p getMonthBegin   b                   export

      d getMonthBegin   pi              d

      d  pDate                          d   const

       /free

            return getPriorMonthEnd(pDate) + %days(1);

       /end-free

      p getMonthBegin   e

 

      p getMonthEnd     b                   export

      d getMonthEnd     pi              d

      d  pDate                          d   const

       /free

            return getPriorMonthEnd(pDate + %months(1));

       /end-free

      p getMonthEnd     e

 

      p getDayOfWeek    b                   export

      d getDayOfWeek    pi             1p 0                     Mon = 0 ... Sun = 6

      d  pDate                          d   const

       /free

            return %rem(%diff(pDate:d'0001-01-01':*days):7);

       /end-free

      p getDayOfWeek    e

 

      p isWeekDay       b                   export

      d isWeekDay       pi              n

      d  pDate                          d   const

       /free

            return getDayOfWeek(pDate) < 5;

       /end-free

      p isWeekDay       e

 

      p isWeekEnd       b                   export

      d isWeekEnd       pi              n

      d  pDate                          d   const

       /free

            return getDayOfWeek(pDate) > 4;

       /end-free

      p isWeekEnd       e

ABOUT THE AUTHOR: Kevin C. Ketzler is a designer, analyst, and project lead for IBM Solutions Practice at Affiliated.

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