One of the cool things about CL (even though I rarely, if ever, use it anymore) is that it is extendable. But one thing it does badly is date manipulation. Effectively, it only handles decimal fields that contain something similar to a date. It is up to the programmer to come up with creative techniques to manipulate date values.

One of the things RPG IV does exceptionally well is date arithmetic. So why not leverage that capability by creating a new CL command that adds a duration to a date value from within CL?

The first thing you have to do is decide in what format the input and output date values will be specified. Since CL uses the job date format extensively, that is the format I've selected for this example command.

The Add Date Duration (ADDDUR) command adds the indicated number of dates to the base date and returns the resulting date to the CL variable specified on the RTNDATE parameter.

You declare a six-digit character variable in CL and populate it with the starting date for the command, calling ADDDUR with the duration you want to add to that date. The duration is added and the resulting date is returned in *JOBRUN format, which is the same as the job date format.

The following is the source for the ADDDUR CL command.

ADDDUR Parameters

DATE is the input date value. This value must be specified in job date format if specified in a CL variable. If a date literal is specified, it may be in MMDDYYYY, MMDDYY, or CYYMMDD format. It accepts dates returned in job date format from the RTVJOBA command.

In addition to a date value, the following special values may be specified:

• *TODAY--Today's date, based on the system date (not the job date)
• *SYSDATE--Same as *TODAY, but can be used to be more clear about the date
• *JOBDATE or *JOBRUN--The job date
• *SBMDATE--The date the job was submitted to the job queue
• *YESTERDAY--The date prior to the current system date
• *TOMORROW--The date following the current system date

DURATION is the number of days you want to add to the date specified on the DATE parameter. The duration may be any number--negative, zero, or positive.

RTNDATE specifies a six-position character CL variable that will receive the returned date value in job date format.

To add seven days to today's system date, do the following:

To retrieve tomorrow's date, do this:

The following RPG IV program, ADDDUR, is the command processing program for the ADDDUR command. It performs the date arithmetic. Specify this program when compiling the ADDDUR command.

Example of Using ADDDUR

In this example, the job's date is retrieved into a six-position character variable named &MYDATE. The RTVJOBA command is used to retrieve the date. RTVJOBA always returns the job date as a character value in the job date format.

Then, the ADDDUR command is called to add one day to the job date. The &MYDATE variable contains the job date from the prior RTVJOBA command. The DURATION parameter indicates that one day is added to the value in &MYDATE, and the new date is returned into the &TOMORROW variable, again in job date format.

ADDDUR helps with one of the most difficult issues with respect to CL: date arithmetic. The results can be used in OPNQRYF, embedded SQL (if available), and user interfaces (display files).

The source code for this article and many other RPG tools is available for free download at the RPGIV.com Web site. Click on the free RPG IV downloads link.

Bob Cozzi is a programmer/consultant, writer/author, and software developer. His popular RPG xTools add-on subprocedure library for RPG IV is fast becoming a standard with RPG developers. His book The Modern RPG Language has been the most widely used RPG programming book for more than a decade. He, along with others, speaks at and produces the highly popular RPG World conference for RPG programmers.