GCC, resize dynamically an array. Possible ?

Hi All,

I've checked my entire C book concerning arrays and I did find nothing related to resizing an array.

Is it possible to directly change the size of an array inside a program ?

(post that kind of questions will probably makes me be considered as a noob ... it's a risk ... but progress nevers happen without risks ;) )

Kindest Regards,
Freddix

@freddix

The only way to resize a memory allocation is to allocate a new piece of memory and copy the data over.

@salass00
Thank you :)

So, I can use this function for Array resizing then ?

@freddix

You can if you allocate your array from the free store.



Note that currently it doesn't clear the memory. If you want it to be cleared (set to all zeros) you should change the 2nd argument of AllocVec to MEMF_CLEAR.

@salass00
Thank you for these clean explanations :)
Now I have all informations to continue my project (until the next question :p)

While arrays are handy for fixed amounts of data, if you find yourself with variable amounts, may I suggest you move to linked lists.

Resizing arrays is extremely hard on memory (typically fragmenting it more and more (although the situation on OS4 is better than previous versions)) and is generally kludgy and very error prone.

A linked list allows you to dynamically add "nodes" to the list, remove them, sort them etc. Check out the "Exec Lists" section of the "RKRM Devices" if you have a copy, or at least check the AddTail(), AddHead(), Remove(), Insert() ,Enqueue(), GetHead(), GetSucc() and GetPrev() function autodocs.

If you dont need the overhead of a full list, a MinList might be more suitable. Again the function autodocs should point you in the right direction, and certainly the RKRMs.

The RKRMs are available in AmigaGuide format on the developer CD2.1 available from a good Amiga shop near you :)

There should be plenty of examples out there too, as code intended for 2.04 is still valid when it comes to linked lists.

Simon

@Rigo:
I already own the Developer CD :p
In fact, my need is to handle a list that can contain from approx 1 element to 65535 elements.

@freddix
Dynamic arrays are a feature added to C99. I think you should consider getting a more up to date C book.