LIKE is Like, Confusing, Man!
December 4, 2002 Timothy Prickett Morgan
Hey, Ted:
IBM is doing it again, and I’m about to pop a vein. I’m getting a data decimal error in an RPG IV program when I access the contents of a data area subfield. The subfield is called PPLANT and it’s defined on the D spec with the LIKE keyword. PPLANT is based on a database file field named IPLANT, which is zoned.
D PlantDS ds D PPlant like(iplant)
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The compiler listing shows IPLANT in the file input and output buffers as being in zoned-decimal format. However, the cross reference shows IPLANT as being in packed-decimal format. Since IPLANT is defined as packed, so is PPLANT. The data in the data area is passed as zoned from another program, so I need PPLANT to be defined as zoned.
Do you know what’s going on or have any solutions besides hard coding the subfield definition?
— John
With the help of IBM’s Barbara Morris, I have an answer for you.
File definitions, whether internally described with I specs or externally described with DDS or SQL, are not field definitions, but descriptions of data in an I/O buffer. When you define a database field as zoned, you are telling the compiler that the field is stored in a zoned format in the file. (In the case of a zoned field in a logical file, the data may be in some other format in the physical file, but the logical file presents it to the program in zoned format.) Note that you are not telling the compiler how the data should be stored in the computer’s memory while the program is running.
The compiler allocates space for each field of each file. If you define a storage format for a field, the compiler allocates the field according to your definition. The following line defines IPLANT as zoned:
D IPlant s 4s 0
But if you do not define a storage format for a field, the compiler uses a default storage format. For numeric fields, the default format is packed decimal. That is why you see IPLANT defined as packed decimal in the cross reference. When your program reads the file, the zoned-decimal value in the buffer is copied to a packed-decimal workspace for IPLANT.
To solve your problem, IBM recommends that you code an externally described data structure for the externally described file that contains IPLANT.
Fchfile uf e disk D ChFileDS e ds extname(chfile) D PlantDS ds D PPlant like(iplant)
The IPLANT field, which is found in file CHFILE, is zoned, so IPLANT is defined as zoned in data-structure CHFILEDS. Since PPLANT is defined to be like IPLANT, PPLANT is also zoned.
— Ted
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