This error that would have been prevented by use strict; use warnings;

I bet your Windows version is 5.10 and your unix version predates 5.10.

>c:\progs\perl588\bin\perl -l 770193.pl
42

>c:\progs\perl589\bin\perl -l 770193.pl
42

>c:\progs\perl5100\bin\perl -l 770193.pl
00
[download]

Before 5.10, a bug caused the "@" in "$#{@a}" to be ignored. It was fixed in 5.10.0.

Fixed:

#!/usr/bin/perl     

use strict;
use warnings;

my @a = (9, 2, 3, 4);   
my @b = ("a", "b");   
    
func(\@a, \@b);   
    
sub func {
   my ($c, $d) = @_;
   print $#{$c}+1, $#{$d}+1, "\n";
  #print $#$c+1,   $#$d+1,   "\n";   \
  #print 0+@{$c},  0+@{$d},  "\n";    > Alternatives
  #print 0+@$c,    0+@$d,    "\n";   /
}
[download]

See Dereferencing Syntax.

Update: Added alternatives and link.
Update: Added results of various version.