Re: Renaming copy member data structure fields

Scott Klement <rpg400-l@xxxxxxxxxxxxxxxx> wrote on 20/03/2006 12:55:51 PM:

> >     D JOBI0600        DS           322
> >     D   @@GRPPRF            137    146
> >
> >     D QUsrParmL       S              4B 0 inz(322)
> 
> 
> The problem here isn't that they added more data to the API, it's that 
you 
> defined a parameter as a BINARY(2) when the API expects BINARY(4).
> 
> In RPG, when you're defining a variable, you define the number of digits 

> that it needs to store.  For example, a packed variable that's defined 
as 
> "7P 0" occupies only 4 bytes of memory, but it stores numbers up to 7 
> digits long.  Similarly, a "4B 0" variable stores up to 4 digits, but 
only 
> occupies 2 bytes of memory.

Right - for some reason I was thinking that the B type was the BINARY the 
API docs were referring to.  Ouch.  Time to RTFM on data types again.

 
> The B data type is crippled. It converts everything to packed whenever 
you 
> use it, which makes it slower, and also means that it's limits are 
defined 
> in decimal digits instead of binary digits.  A true binary type is much 
> faster, and isn't confined by decimal digits.  In RPG, data type I and U 

> are true binary types.  Use them instead.

Thanks - I'll keep that in mind.

 
> What does it overwrite?  What does it corrupt?  Who knows. It's whatever 

> happens to be after your data structure in memory.  It could be memory 
> that's not currently being used. It could be other variables in your 
> program.  Or even in another program.  Or even memory in use by the 
> operating system.  And the API just overwrote it because you told it the 

> variable was longer than it really was.

Yikes!  You mean there's no such thing as a segfault in i5/OS?!

Thanks for the comprehensive response,
Adam
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