foreach my $file (@nbdc_files){
    open \*FILE, "./$nbdc_dir/$file" || die "Can't open ./$nbdc_dir/$file";
    push @nbdc_filehandles, \*FILE;
     # etc.
}


##</code><code>##

foreach my $file (@nbdc_files){
    open my $fh, "./$nbdc_dir/$file" || die "Can't open ./$nbdc_dir/$file";
    push @nbdc_filehandles, $fh;
     # etc.
}