Question

in RPG III I need to store an huge array in a file. The maximum fieldlength is 256, thus I defined the file with 16 fields of 250 chars long each. Is there a way to put the 1000 values of the array into the 16 fields without moving? Just like the REDEFINES in COBOL?

array in the program:

 E                    MPDV     1000  4   

Specicifation of the file:

 D000001                                           1   4 WRPMOD 
 D000002                                           5 254 W01PDV 
 ... etc. until     
 D000017                                        37554004 W16PDV   

In Cobol I would write:

 01 MPDV-TOP.
     03 MPDV-ARR OCCURS 1000.
        05 MPDV PIC X(4).
  01 WRPREC REDEFINES MPDV-TOP.
     03 W01PDV PIC X(250).
     .... ETC. UNTIL
     03 W16PDV PIC X(250).

Reading the file I get the array MPDV with it’s values and with values in MPDV I can write the file.

my solution looks like this:
an extra array

    E                    MPX        16250               MPDV REDEF   

and lots of moves:

C                     MOVELMMEMOD    WRPMOD    
C                     MOVEAMPDV      MPX       
C                     MOVELMPX,1     W01PDV    
C                     MOVELMPX,2     W02PDV    
.... etc until
C                     MOVELMPX,16    W16PDV  
C                     WRITEWRPASM         

and reverse for reading.

Answer 1

Use a Data Structure to overlay the individual fields into the main field:

IMPDV        DS                                      
I                                        1 250 W01PDV
I                                      251 500 W02PDV
I                                      501 750 W03PDV
                      . . .
I                                     37514000 W16PDV

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For more information I recommend the following resources:

IBM i information center
ILE RPG Programmers Guide
ILE RPG Language Reference

Safari Books Online
The Modern RPG IV Language