Hi Mahatmas,

the target is to get a string into an array.

split does it perfectly but is slow.

unpack is extremly fast but produces 97, 98, 99 instead of a,b,c

so you have to chr() it to get 'a' out of 97 - again slow

What would you suggest?

A sample code:

use strict;
use warnings;

        # Fill a buffer with bytes
my $begin = time();
my $buffer = '';
for( 0 .. 10_000 ) { $buffer .= "abcdef\x00ghik"; }
        #
        # Split is slow
        #
print "split 20 times\n";
for( 0 .. 20 ) {
        print "loop $_\n";
        my @a = split( //, $buffer );
}
printf( "split consumed %d second(s)\n", time() - $begin );
$begin = time();
        #
        # pack is extremly fast
        #
print "pack alone\n";
for( 0 .. 20 ) {
        print "loop $_\n";
        my @a = unpack( "C*", $buffer );
}
printf( "pack consumed %d seconds\n", time() - $begin );
$begin = time();
        #
        # pack is extremly fast but needs chr() to get characters - slow!
        #
print "pack and chr in map\n";
for( 0 .. 20 ) {
        print "loop $_\n";
        my @a = unpack( "C*", $buffer );
        map{ $_ = chr( $_ ) } @a;
}
printf( "pack and chr in map consumed %d seconds\n", time() - $begin );
exit;

In reply to Convert string to array - performance challenge by rtillian

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