RE: API- Userspace pointer Question -- RPG400-L

Tommy,

s0300Ptr=s0300Ptr+%Size(SPLF0300)

Where s0300Ptr is set to the original offset just add the %size of the
DS returned.

The List APIs (including QUSLSPL) do not return the entries in fixedpositions of the user space. The documentation states that these positionsare variable -- and the API passes you a variable that indicates the startof the data, how many entries there are, and how far apart these entriesare.

The emphasis in the above paragraph should be on "variable". While it'strue that IBM doesn't usually change these positions except when a releasechanges, they'd be well within their rights to change them at any time.

For example, perhaps the entries would be a different distance apart,depending on the values of the input parameters. Or maybe the distancebetween each entry would change, based on a PTF.

The problem with your code example is that you've got that distancehardcoded in your program, and you're ignoring what the system tells you.


I'm referring ot the following statement:

  s0300Ptr=s0300Ptr+%Size(SPLF0300)

%size() is a hard-coded value. It's set at compile time, and won't everchange no matter what you do.

It's not any more difficult to use a variable for the offset instead ofthe size of your data structure! Assuming that the entry size field is ina variable called EntrySize you'd code:


  s0300Ptr=s0300Ptr+EntrySize

So my question is.... why do it wrong? Even if you don't mind fixingit with each release upgrade or PTF or whatever else breaks your code,how is it saving you anything to type "%size(SPLF0300)" instead of

"EntrySize"?

So this is the rule of thumb: When an API sends you an offset, size ordisplacement, don't ignore it and hard-code the position. Use the valuethat the API sent you.