Question

I am having trouble with my array of references which point to another array. Here’s a snippet of my code:

# @bah is a local variable array that's been populated, @foo is also initialized as a global variable
$foo[9] = \@bah; 

# this works perfectly, printing the first element of the array @bah
print $foo[9][0]."\n"; 

# this does not work, nothing gets printed
foreach (@$foo[9]) {
    print $_."\n";
}

Answer 1

Always use strict; and use warnings;.

The @ dereference takes precedence, so @$foo[9] expects $foo to be an array reference and gets element 9 from that array. You want @{$foo[9]}. use strict would have alerted you that $foo was being used, not @foo.

For some easily memorizable rules for dereferencing, see http://perlmonks.org/?node=References+quick+reference.