Unable to pass a hash and a string to a function, together in perl! - perl

Question

I am basically trying to pass a string and a hash to a subroutine in perl.
sub coru_excel {
my(%pushed_hash, $filename) = #_;
print Dumper(%pushed_hash);
}
But it seems data is getting mixed up. The dumped data also includes the $filename. here is the output.
...................
$VAR7 = 'Address';
$VAR8 = [
'223 VIA DE
................
];
$VAR9 = 'data__a.xls' <----- $filename
$VAR10 = undef;
$VAR11 = 'DBA';
$VAR12 = [
'J & L iNC
..................
];
Here is how I called the subroutine.
coru_excel(%hash, "data_".$first."_".$last.".xls");

Answer 1

Arguments are passed to subroutines as one undifferentiated list.
One solution is to reverse the order of the arguments so that the scalar is first.
sub coru_excel {
my($filename, %pushed_hash) = #_;
}
coru_excel("FILE_NAME", %hash);
Another approach is to pass the hash by reference:
sub coru_excel {
my($pushed_hash_ref, $filename) = #_;
}
coru_excel(\%hash, "FILE_NAME");

Answer 2

You could pass the hash as a reference:
sub coru_excel {
my($pushed_hashref, $filename) = #_;
print Dumper(%$pushed_hashref);
}
coru_excel(\%my_hash, $file);
Or you could give special treatment to the final argument before you initialize the hash:
sub coru_excel {
my $filename = pop #_;
my(%pushed_hash) = #_;
print Dumper(%pushed_hash);
}

Answer 3

You have to pass the hash as a reference:
coru_excel(\%hash, "data_".$first."_".$last.".xls");
You use it like this:
sub coru_excel {
my($pushed_hash_ref, $filename) = #_;
my %pushed_hash = %{$pushed_hash_ref};
print Dumper(%pushed_hash); # better: \%pushed_hash or $pushed_hash_ref
}
See perlreftut for a tutorial on references and perlref for further information.
Dumper also produces better usable information when you pass a hash (or array) reference.

Answer 4

See also the related Perl FAQ. From the command line:
perldoc -q pass
or
perldoc -q hash
Refer to perlfaq7: How can I pass/return a {Function, FileHandle, Array, Hash, Method, Regex}?

Answer 5

A small program demonstrating how to do this using reference notation when passing the hash and shift in the subroutine to pull out the parameters.
#!/usr/bin/perl -w
use strict;
sub coru_excel(%$);
my %main_hash = ('key1' => 'val1', 'key2' => 'val2');
my $first = "ABC";
my $last = "xyz";
coru_excel(\%main_hash, "data_" . $first . "_" . $last . ".xls");
exit;
sub coru_excel(%$)
{
my %passed_hash = %{(shift)};
my $passed_string = shift;
print "%passed_hash:\n";
for my $k (keys %passed_hash) {
print " $k => $passed_hash{$k}\n";
}
print "\$passed_string = $passed_string\n";
return;
}