Dynamic creation of hashes

shamala has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks, Would like to know how to create hashes dynamically...here's what i have:

#!/usr/bin/perl
my %hash_mnt=();
@Mounts= `mount`;
$count=0;
 foreach $mount(@Mounts){
  $count++;
  print "$count\n";
  ($mnt_key,$mnt_val,$mnt_acc)=(split(/\s+/,$mount))[2,0,6];
                                                                      
+                                                       <li> I want to
+ create a hash here </li>
<li> multidimensional hash with mnt_key as key and mnt_val and mnt_acc
+ as values</li>
   
  }
[download]

I tried :

#!/usr/bin/perl
my %hash_mnt=();
@Mounts= `mount`;
 foreach $mount(@Mounts){
  ($mnt_key,$mnt_val,$mnt_acc)=(split(/\s+/,$mount))[2,0,6];
  push( @{$hash_mnt{$mnt_key}[0]}, $mnt_val );
  push( @{$hash_mnt{$mnt_key}[1]}, $mnt_acc);
                                                                      
+                                                       
  }
[download]

But this isnt working

Am i missing something???

Thanks

Shamala

Comment on Dynamic creation of hashes Select or Download Code

Replies are listed 'Best First'.
Re: Dynamic creation of hashes by Aristotle (Chancellor) on Aug 14, 2004 at 08:03 UTC
What do you mean by "not working"? It works quite fine for me. `use Data::Dumper; print Dumper \%hash_mnt; __END__ $VAR1 = { '/proc/bus/usb' => [ ['usbfs'], [undef] ], '/sys' => [ ['none'], [undef] ], '/' => [ ['/dev/hda1'], [undef] ], '/dev/pts' => [ ['none'], [undef] ], '/tmp' => [ ['/dev/hda5'], [undef] ], '/proc' => [ ['proc'], [undef] ], '/home' => [ ['/dev/hda6'], [undef] ] };` [download] Do you mean that this structure is not what you wanted? It seems most sensible that you'd want a hash of arrays instead of the hash of arrays of arrays. Maybe like so? `foreach $mount(@Mounts){ ($mnt_key,$mnt_val,$mnt_acc)=(split(/\s+/,$mount))[2,0,6]; $hash_mnt{$mnt_key} = [ mnt_val, $mnt_acc ]; } use Data::Dumper; print Dumper \%hash_mnt; __END__ $VAR1 = { '/proc/bus/usb' => [ 'usbfs', undef ], '/sys' => [ 'none', undef ], '/' => [ '/dev/hda1', undef ], '/dev/pts' => [ 'none', undef ], '/tmp' => [ '/dev/hda5', undef ], '/proc' => [ 'proc', undef ], '/home' => [ '/dev/hda6', undef ] };` [download] Makeshifts last the longest.	[reply] [d/l] [select]
Re: Dynamic creation of hashes by wfsp (Abbot) on Aug 14, 2004 at 08:07 UTC
perldsc says: `push @{ $HoA{"flintstones"} }, "wilma", "betty";` [download]	[reply] [d/l]
Re: Dynamic creation of hashes by jdalbec (Deacon) on Aug 14, 2004 at 14:04 UTC
Should 6 be 5 (or even 4)? On my Linux system "mount" returns: `/dev/hda6 on / type ext3 (rw) 0 1 2 3 4 5` [download] so naturally `(split(...))[6]` is undef. Others have commented on your possible misunderstanding of how `push` works. Update: I guess it should be 5 since you're assigning to `$mnt_acc`.	[reply] [d/l] [select]