Re: Variable length MODS

[Jim Langston <jimlangston@xxxxxxxxxxxxxxxx>]

Actually, James, I have used that structure definition in C.  Although the
syntax may be a bit off.  

char * array[];

maybe?  Although I think

char array[];

is actually legal.  A pointer to an array of char of undetermined size. 
Which is exactly what I was talking about.

C gurus wish to clarify?

Regards,

Jim Langston

James David Rich wrote:
> 
> On Tue, 17 Apr 2001, Jim Langston wrote:
> 
> > Does it really matter how many elements are in an array that is being
> > used as a pointer anyway?
> 
> If a DIM is given it should be honored (i.e. that amount of space should
> be allocated) but an ALLOC should be able to increase the size, allowing
> the program to reference occurences beyond those given in the DIM.
> 
> I believe that the structure definition given below is illegal in other
> languages, i.e. you can't have:
> 
> char array[];
> 
> so a DIM with no size is probably bad.
> 
> > This is pseudo code
> >
> > D SomeStructure  DS             DIM() BASED(SomePointer)
> > D SomeString         10A
> > D SomeInt            10U
> > D SomeZoned           9S 0
> > D SomePointer     S    *
> >
> > D SomeCounter         9P 0
> > D SomeMax             9P 0
> >
> > C            Eval    SomePointer = SomeAddressToSomeArray
> > C            Eval    SomeMax = MaxRangeOfTheArrayPointingTo
> 
> [snip]
> 
> > The whole point being, RPG or the AS/400 shouldn't care what the upper
> > limit is.  It does not have to allocate any memory, since we are using a
> > pointer anyway, and just looking at memory that's already there.  The
> > program math is fairly simple behind the covers, the array element X
> > starts at SizeOfStructure * (X - 1) + 1
> 
> It should care if the struct is being accessed "the old way", i.e. not
> pointer based.  If the definition is not "BASED" then the current way is
> fine.  If the struct is pointer based then all bets are off and accesses
> outside of allocated memory should result in a segmentation fault (or
> whatever).
> 
> James Rich
> james@eaerich.com
> 
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