RPG-将数字DS复制到Alpha DS

Question

I want to copy Numeric DS to Alpha DS. First Idea was MOVEA, but that does not seem to work. Error: "The Factor 2 or Result-Field of a MOVEA does not refer to an array"

D Alpha       DS                                                 
D  TBR1                         5A                                  
D  TBR2                         5A                                  

D Num         DS                                                 
D  TBR1N                        5  0                                
D  TBR2N                        5  0                                

C                   MOVEA     Alpha     Num

Answer 1

There seem to be a lot of misconceptions about data structures in RPG. In the past month there have been two questions because someone thought he could coerce the data structure to be a UCS2 value. It won't work. The data structure is a fixed length character field using the job's CCSID. The fact that it has some internal structure is meaningless if you are using the data structure name as your variable.

This seems to be compounded by fixed form RPG's ability to implicitly define a field as character or numeric without giving it a data type. Stand alone fields and data structures treat this condition differently. See the following table:

field type  | decimal positions | Implicit data type
----------------------------------------------------
stand alone |    blank          |   A
            |  not blank        |   P
----------------------------------------------------
data        |    blank          |   A
 structure  |  not blank        |   S

So for your definitions:

D Alpha       DS                                                 
D  TBR1                         5A                                  
D  TBR2                         5A                                  

D Num         DS                                                 
D  TBR1N                        5  0                                
D  TBR2N                        5  0

Alpha is CHAR(10)
TBR1 is CHAR(5)
TBR2 is CHAR(5)
Num is CHAR(10)
TBR1N is ZONED(5 0)
TBR2N is ZONED(5 0)

There are no arrays so you can not use MOVEA with any of these on both sides., but MOVEL would work to assign Alpha to Num like this:

C                   MOVEL     Alpha     Num

That being said, you should not be using Fixed Form any more. All supported versions of the OS support Free Form RPGIV, and you can gain some advantages by using it. Specifically to this case, the implicit numeric data type is not possible in Free Form. So you would have something like this:

dcl-ds Alpha Qualified;
  tbr1       Char(5);
  tbr2       Char(5);
end-ds;

dcl-ds Num   Qualified;
  tbr1n      Zoned(5:0);
  tbr2n      Zoned(5:0);
end-ds;

Num = Alpha;

Data types are now explicit, and you can even qualify your data structures so that you can say something like this:

num.tbr1n = %dec(alpha.tbr1:5:0);

Answer 2

First off, there's no such thing as a "numeric DS".

A data structure in RPG is just a collection of bytes. And since the compiler doesn't have a BYTE type, it simply treats it as SBCS characters.

You're issue is that your numeric subfields are defaulting to packed decimal. So your DS named NUM is only 6 bytes.

Define them as ZONED instead, so that both DS will be 10 bytes.

 D Alpha           DS                                                 
 D  TBR1                          5A                                  
 D  TBR2                          5A                                  

 D Num             DS                                                 
 D  TBR1N                         5S 0                                
 D  TBR2N                         5S 0

   Num = Alpha;

But this kind of code really isn't a good idea in RPGIV..

Why can't you explicitly convert?

tbr1n = %dec(tbr1:5:0);
tbr2n = %dec(tbr2:5:0);