Re: Getting into pointers

Using %alloc() is the right way.

But this doesn't make sense:
wLen = %LEN ( wMrsAdh ( 1 ));

where is wMrsAdh defined?

Then you use a "magic number" here, which is never a good idea.
MyPtr = %ALLOC ( wLen * 100 );

If you wanted to do it that way, a better idea would have been the %elem() bif.

However, I would have just coded:

MyPtr = %ALLOC ( %size(MyDS:*ALL));


HTH,
Charles

On Wed, Aug 12, 2009 at 8:41 AM, David FOXWELL<David.FOXWELL@xxxxxxxxx> wrote:

Hi,

I just wrote my first program ever that passed a pointer from one program to another. I used it to access a data structure in the calling program that was alimented by the program being called. I won't explain why I did not just pass the data structure as a parameter. Anyway, it seems to work. I was a little surprised and found it good fun. However, having rather stumbled upon the solution when it didn't work, I ask the experts out there for confirmation :



Code simplified.
D PGM2            PR                  EXTPGM ( 'PGM2' )
D OutParm                         *


D MyDS            DS                  LIKEDS ( gMyOtherDS ) DIM ( 100 )
D                                     BASED ( MyPtr )
D MyPtr           S               *

 /free

 PGM2 ( MyPtr );

/end-free



This crashed because I understand I need to allocate storage for MyPtr before the call.

So I inserted this and it worked :
 wLen  = %LEN ( wMrsAdh ( 1 ));
 MyPtr = %ALLOC ( wLen * 100 );

Is this the right way to initialize the pointer?

Thanks.
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