Gary wrote:
> I hope this is the right place to ask this question.
>
> So I've seen code like this
>
> for (1..10) {
> print $_
> }
>
>
> What's going on behind the scenes with that?
In modern versions of Perl that is equivalent to:
for ( $_ = 1; $_ >= 10; ++$_ ) {
print $_
}
In older versions of Perl that would create the list in memory first before it
iterated over it.
> Is it creating an array?
No.
perldoc -q "What is the difference between a list and an array"
> What if I want to use
>
> for (1..1000000) ?
>
> Also, What's the internal structure of Perl arrays?
perldoc perl
[ snip ]
Internals and C Language Interface
perlembed Perl ways to embed perl in your C or C++
application
perldebguts Perl debugging guts and tips
perlxstut Perl XS tutorial
perlxs Perl XS application programming interface
perlclib Internal replacements for standard C library
functions
perlguts Perl internal functions for those doing extensions
perlcall Perl calling conventions from C
perlapi Perl API listing (autogenerated)
perlintern Perl internal functions (autogenerated)
perliol C API for Perl's implementation of IO in Layers
perlapio Perl internal IO abstraction interface
perlhack Perl hackers guide
Also have a look at all the B::* and Devel::* modules.
> I can't find anything on that.
> I'm curious about how much time it takes to do something like insert into the
> middle ofan array. Is that O(1)?
Yes.
$ perl -le'
my @array = 0 .. 20;
print "@array";
splice @array, 10, 0, "X", "Y", "Z";
print "@array";
'
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
0 1 2 3 4 5 6 7 8 9 X Y Z 10 11 12 13 14 15 16 17 18 19 20
John
--
Perl isn't a toolbox, but a small machine shop where you can special-order
certain sorts of tools at low cost and in short order. -- Larry Wall
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