Updating Numeric DTAARA in RPGLE


Oct 17

Updating any numeric DTAARA in RPGLE is slightly different in RPG /FREEFORMAT than in the good old fashioned column based RPG/400. Using RPG ILE, data structures are treated as character data. The nature of a data area is that its a string of data that can contain a mixture of various data formats.

If we play with the local data area (*LDA) its essentially a long string of stuff:

Updating Numeric DTAARA

Of course this string of data can be populated with a mixture of values:

Updating Numeric DTAARA in RPGLE 1
*LDA populated with different datatypes

So, since a DataStructure in RPG is always character – how do we update a numeric only data area?

Updating a Numeric Data Structure in RPG/FREE

Let’s stop my waffle and look at an example. That is why you are here after all.

I have a numeric DS called EMLRECNUM, cunningly designed to hold an increment count of the number of emails floated out into the ether.

Updating Numeric DTAARA in RPGLE 2

Annoyingly I can define a Data Structure like this and it looks correct:

 dcl-ds EmlRecNum dtaara('EMLRECNUM') qualified;     
    count zoned(9:0);                                 
 end-ds ;    

and when I try to update it like this:

 in *lock EmlRecNum;       
 emlrecnum.count += 1;           
 out EmlRecNum;     

Most annoyingly it all compiles and looks/feels like a jolly simple peace of RPG code.

But when you run it… oh boy... big wet explosion follows:

Updating Numeric DTAARA in RPGLE 3
Splattery death of updating a numeric DS

How do we fix this?

If the only thing in the DTAARA is a *DEC value, use a stand-a-lone field rather than a data structure:

dcl-s EmlRecNum packed(9:0) dtaara('EMLRECNUM'); 

We treat the update in the exact same way:

in *lock EmlRecNum;
   emlrecnum += 1;
out EmlRecNum;

And thats that.

But it made me scratch my head for waaay too long. So, i hope it helps some other propellor headed IBM-i programmer type chaps or chappettes or transchappies out there 🙂

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About the Author

IBM i Software Developer, Digital Dad, AS400 Anarchist, RPG Modernizer, Alpha Nerd and Passionate Eater of Cheese and Biscuits. Nick Litten Dot Com is a mixture of blog posts that can be sometimes serious, frequently playful and probably down-right pointless all in the space of a day. Enjoy your stay, feel free to comment and in the words of the most interesting man in the world: Stay thirsty my friend.