RE: QWCCVTDT Weirdness, solved! -- RPG400-L

I understand how you use alloc to get more space assigned to the
variable than the d-spec definition would normally allow. Since I prefer
the user space method, how would I set that up?

The only difference between the user space and alloc method is the way youallocate the space. Instead of calling %alloc() to get the space, you callQUSCRTUS and QUSPTRUS (and maybe QUSCUSAT, if you want it to auto-extend)

Let's say my user space pointer is USP_Ptr.
I'll need to define a variable based on that.
So,

D MyVar         ??????A  Based(USP_Ptr).

How big do I make the variable. I kept thinking that if I make it the
largest I could define on the D-spec (32767) that's all the API would
return for me.

The API doesn't know how big your variable is. It doesn't have any way toread your source code and check that. All it knows is

a) The spot in memory where it's stored (since that's what gets passedwhen you pass a parameter)


b) The length that you pass in the "length of receiver variable".

Or - is the 'length of receiver variable' (staying with the QMHRDQM APIexample) the key? Will the API use however much space I tell it to inthat variable, regardless of the definition of MyVar.

Correct, it'll use as much space as you the "length of receiver variable".(Unless of course, it needs less space than that... but it'll never usemore)



 Example.


D MyVar             1A   Based(USP_Ptr).
D MyVarLen         10I 0 Inz(1048544)                      *-or whatever
size I want-*

Then when the API is called, it will start putting data into MyVar but
continue as far as the MyVarLen lets it go? If this is the case, I can
run with that.

That's correct. (Assuming that you actually pass these as parameters tothe API, rather than just declaring them on the D-spec)

I think that's a little obscure myself, but I'll agree that it's alittle more clear than my weird pointer structure I'd forced to workbefore.

You have to accept the notion that the ONLY thing that gets passed whenyou pass a parameter is the memory address.

(And this isn't an attribute of APIs -- it's just how parameters work onthe iSeries. It's the same notion that's used when you pass parametersfrom program or program or from the command line to a program.)

As long as you've accepted that fact, then it makes perfect sense whypassing a parameter and a separate length for that parameter, will allowthe API to deal with any size field.