for my $i (0..$#array) {
   print("Element $array[$i] was found at index $i\n");
}
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for my $i (0..$#array) {
   my $e = $array[$i];
   print("Element $e was found at index $i\n");
}
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for my $i (0..$#array) {
   for my $e ($array[$i]) {
      print("Element $e was found at index $i\n");
   }
}
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The default iterator variable in a foreach loop if no other variable is supplied.

use strict;
use warnings;

for (1..5) {
    print 2 * $_, " ";
}
print "\n";

__END__
2 4 6 8 10
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You can find a list of special variables—like $.—in perlvar.

There is probably no such variable, but you can play with a range operator .. in scalar context:

my @letters = qw(alfa beta gama);
for my $letter (@letters){
   warn "iteration is ", scalar($0 .. !$0);
}
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The $0, resp. !$0 are just expressions which are allways true, resp. allways false. Unfortunately you cannot use 1, 0 because they are given some special meaning by the range operator.

Although this "trick" works, it is not particularly self-explainable.

Wow! That could be really useful. How the heck does it work and is it documented anywhere?

Update - never mind...

After some quick research and testing I see that ($0 .. !$0) only increments as it's used. So you can't just pop it into an if statement somewhere to get the current iteration (which would be very useful). You might as well just dedicate a new variable to keep count.

Interesting none the less.

Be aware. I just get burned by this hack - the range operator iterates all over its lifetime.

sub iterate {
    for my $item ( @_ ){
        warn 'iteration '. ($0 .. !$0), "\n";
    }
}

iterate( qw(a b c) );
iterate( 1, 2, 3, 4);
iterate( 0 );
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yields

iteration 1
iteration 2
iteration 3
iteration 4
iteration 5
iteration 6
iteration 7
iteration 8
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