for(my $i = 0; $i < @ARGVl $i++) {
    if($ARGV[$i] =~ /meets some condition/) {
        # ack! the index has been offset
        $i += 2;
    }
}

##</code><code>##

for my $i (0 .. $#ARGV) {
    if($ARGV[$i] =~ /meets some condition/) {
        # doesn't matter as $i will be set again in the next iteration
        $i += 2;
    }
}

##</code><code>##

use Benchmark qw(cmpthese); 
my @list = 1..10000;
my $r;

cmpthese(-10, {
    cstyle => sub {
        for(my $i = 0; $i < @list; $i++) {
            $r = $list[$i];
        }
    },
    perlstyle => sub {
        for my $i (@list) {
            $r = $i;
        }
    }
});

__output__

Benchmark: running cstyle, perlstyle, each for at least 10 CPU seconds...
    cstyle: 15 wallclock secs (10.57 usr +  0.05 sys = 10.62 CPU) @ 36.06/s (n=383)
 perlstyle: 15 wallclock secs (10.10 usr +  0.03 sys = 10.13 CPU) @ 86.77/s (n=879)
            Rate    cstyle perlstyle
cstyle    36.1/s        --      -58%
perlstyle 86.8/s      141%        --