It's more efficient (especially in terms of memory) to keep the two things contiguously in memory than to have to chase an additional pointer to the array. In C it looks almost the same (arrays and their pointers are both specified by naming the arraym but "sizeof" will act differently for instance.
And yes, the "growable" part of a structure has to be the last thing for it to work. I learned how to do this in 1981 but scalars only go back to around 1997. cheers M On Fri, Feb 21, 2014 at 02:23:43PM -0500, Jonathan Wilkes wrote: > On 02/21/2014 09:00 AM, Ivica Bukvic wrote: > > > >Because this way you can reference data points with sc_vec+n as > >opposed to dealing with single or double linked lists (since > >sc_vec can be an array). > > > > If sc_vec is a pointer then you can access data points using the > same technique, which is pointer math after all. > > For everyone's amusement, here's an exercise in my own rank > speculation: something about a t_word array aligning on boundaries > in a way that you wouldn't be able to guarantee with a pointer to a > t_word. So if you can guarantee there won't be padding you save > memory in 1981. > > Is it something like that, Miller? > > And do scalars actually go back to 1981, or that's just around the > time you learned the technique? > > Also-- this technique means that for sc_vec[1] its position inside > the struct suddenly become relevant. That is, if you put > sc_template as the last member field you'd be indexing into the > wrong place when you tried to read/write sc_vec data. Is that > right? > > -Jonathan > > >On Feb 21, 2014 7:26 AM, "Charles Goyard" <c...@fsck.fr > ><mailto:c...@fsck.fr>> wrote: > > > > Hi, > > > > Sorry for this question, but why isn't sc_vec a good old pointer ? > > > > > t_gobj sc_gobj; /* header for graphical object */ > > > t_symbol *sc_template; /* template name (LATER replace with > > pointer) */ > > > t_word sc_vec[1]; /* indeterminate-length array of > > words */ > > > } t_scalar; > > > > > > How is a static t_word array of size 1 an indeterminate-length > > array? Is its placement as the last member of the struct required? > > > > _______________________________________________ > > Pd-list@iem.at <mailto:Pd-list@iem.at> mailing list > > UNSUBSCRIBE and account-management -> > > http://lists.puredata.info/listinfo/pd-list > > > > > > > >_______________________________________________ > >Pd-list@iem.at mailing list > >UNSUBSCRIBE and account-management -> > >http://lists.puredata.info/listinfo/pd-list > > _______________________________________________ > Pd-list@iem.at mailing list > UNSUBSCRIBE and account-management -> > http://lists.puredata.info/listinfo/pd-list _______________________________________________ Pd-list@iem.at mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
