unpack versus split

[habicamasuchi]

I am having trouble using unpack instead of split. I know that unpack is quite a bit faster than split and therefore would rather use unpack. The particulars:

open(FILE,"file") or die "No such file";
open(OUT,">outfile";
while(<FILE>) {
$form = unpack("x145 A1", $_);
next unless ($form eq "O");
$_ = unpack("A1000", $_);
@data = unpack("C*",$_);

The problem is with this last line. I want to split the string (which is 2000 characters long) so that each character will be a element of the array. split(//) works but is really slow. unpack("C*",$_) works but gives me the numerica ASCII values instead of the actual characters. How do I get unpack to split the string into individual characters?

 

[icrf]

Does running map to convert back gain you any speed over the standard split //?

@data = map chr, unpack('C*', $_);
@data = map pack('C', $_), unpack('C*', $_);

________________________________________
Andrew

I work for a gift card company!

 

[TrojanWarBlade]

Correct me if I'm wrong but you want an array of 1000 elements, each holding a character from the first 1000 characters of a 2000 character string.

If that's the case,

my $data = unpack("A1" x 1000, $_);

I do question though what on earth you'd need this for.
Also, I'm not sure if the Perl compiler will make the "A1" x 1000 into a constant, so if performance is an issue and you're gonna process lots of records, I suggest you setup a template scalar:

my $template = "A1" x 1000;
open(FILE,"file") or die "No such file";
open(OUT,">outfile";
while(<FILE>) {
    my $form = unpack("x145 A1", $_);
    next unless ($form eq "O");
    my @data = unpack($template, $_);

Let me know if this works

Trojan.