RE: Extract variable string from a based DS using a pointer -- RPG400-L

Thanks Bob,

This data structure is one of many that can be filled in by an API. I guess I didn't previously understand about no storage being allocated when using BASED.

Let me rephrase your answer.

If I declare TextData as a 32K variable then assign a value to the textPtr, as long as I don't excede the textLen (as returned by the API) when I reference TextData, I should be okay. Any TextData characters beyond the TextLen specified can be anything in that happens to be in that area of memory, but I do not have a full 32K field allocated. Do I have this right?

I thought about a VARYING field, but since this is a structure returned by an API, I didn't think the variable field would be populated correctly by the API (it would return data in the two length bytes).

At 03:40 PM 12/16/2004, you wrote:

Are you trying to simulate a VARYING field? Looks like it to me.

D TextDS    DS                       BASED(textPtr)
D  TextLen                     5I 0
D  TextData                32766A


If you use BASED, no storage is allocated for TEXTDS, so it does not matter
if you declare TEXTDATA as a 32K variable. That way SUBST and other
operation will work the way you want.

If you want to NOT use this suggestion, and you simply want to copy from
that memory location, use this:

  Eval     memcpy(%addr(target) : textPtr + 2: some-length-here )

But why not just use a VARYING field?


Dave Murvin
DRM Enterprises, Inc.

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