use strict;
use vars qw($program);

$program={};

##</code><code>##

sub main {
  my $program;
  ...
  $program={};
  parse_program("source.c", $program);
  print_functions($program);
  do_other_stuff($program);
}

##</code><code>##

sub print_functions {
  my $program=shift; # this is not needed if $program is
                     # global, obviously
  my $functions=$program->{functions};

  # and now you can just use $functions to access the data
}