A Perl n-D structure is not an "array", certainly not for n>1. To me an
array has a fixed, regular memory layout, like a checker or chess board. If I
am on row 4, square 6 and I want to know what row 3, square 5 contains,
I just go: left 1 and up 1 from where I am at. That's it!
in reply to Re: why the array index has to start at 0??
in thread why the array index has to start at 0??
A Perl LoL
(List of List), a Perl 2-D structure, doesn't work that way.
I've written FORTRAN code with 2-D arrays and some ASM code,
but never any C code yet and certainly not any Perl code. It is simply not the
way that it is done.
In Perl, every dimension until the last one is a
"reference". It works the same as 'C'. If you take a 'C' class, somewhere
along the path to the first year, you will learn that this: int x ;
is total BS! There is a HUGE flaw with this because you cannot pass "x" to a
subroutine! How big is it? What do I do? The answer to this is similar to
how Perl does it. The first dimension is a list of pointers to the 2nd
dimension. In the case of a 2-D array, you have to allocate memory
for the list of pointers to lists and also for the "rows" themselves and
it's a pretty huge hassle!
Anyway what you wind up with is a "list" of pointers to
"lists". Now I can give you "x" and tell you to add say 5 to every element in
this structure. I don't have to tell you how many rows there are, I don't have to tell
you how many columns there are (and they may even vary between rows).
automates a lot of this "grunt work". A Perl 2-D structure is not an array. It is a
list of lists.