$ perl -e 'my $i = 0; print $i++, " " while $i < 10;'
0 1 2 3 4 5 6 7 8 9
~
$ perl -e 'my @array = 1..10; print 2*$_, " " for @array;'
2 4 6 8 10 12 14 16 18 20
~

##</code><code>##

for (@array) {
     print $ERRORS "Error: value $_ is negative\n" and next if $_ < 0;
     push @valid_vals, $_;
}

##</code><code>##

5 statement if condition else other_statement;