storing variable names in an array

[scifiaddict]

Howdy,

I'm storing a group of strings in an array that are names of variables. Something like ......

my $file1 = "tom";
my $file2 = "bob";
my $file3 = "joe";

my @names = ("file1", "file2", "file3");

I now want to change the value of $file2 from "bob" to "sam", but I would like to do it using only the information in the array? Seems like it should be easy, just can't figure it out.

Thanks.

[thundergnat]

Unless you need the names of the files in some specific order that is not easily obtained through sorting, you are much better off storing the file names in a hash.

my %names = (file1 => "tom", file2 => "bob", file3 => "joe");

Then if you need to change what file2 points to just do it directly.

$names{file2} = "sam";

To iterate over the %names...

for (keys %name){
   print "$_ = $names{$_}\n";
}

[kirbyk]

It's possible to do that, but it's not really the easiest way.

Consider using a hash instead:

my %files = (
     'file1' => 'tom',
     'file2' => 'bob',
     'file3' => 'joe',
);

$files{'file2'} = 'sam';

Alternately, just store your filenames in the array (if order is important), like:

my @names = ('tom','bob','joe');
$names[1] = 'sam';

Adding the additional step of the array of variable names is usally the wrong path to go down.

[davidrw]

The hash suggestions above are good ones .. for reasons not to use other 'solutions', see this thread: Using a scalar as an array name
(and there's been a couple/few nodes since that one, too, on the same topic but i don't have them handy)

[tlm]

In addition to the hash-based solutions offered, there's also

my @file = qw( tom bob joe );

so instead of referring to, e.g., $file1, you'd refer to $file[0]. You can change the values of these variables programmatically, by maniplulating the integers corresponding to the array indices. This node has some interesting thoughts on the perennial desire to manipulate variable names programmatically.

[Joe_Cullity]

Sound like you'd be better off using a hash table

#!/usr/bin/perl
%a_hash    = ( "file1", "tom", "file2", "bob", "file3", "joe");  

$vale_from_hash = $a_hash{"file2"}; # Should return "bob"  

$a_hash{"file2"} = "Sam"; # file2 should now be "Sam"  

$vale_from_hash = $a_hash{"file2"}; # Should now return "Sam"  

print( %a_hash ); # Pairs will be matched but usually out of order you
+ expect

[djohnston]

You can probably accomplish what you're asking using soft references. This is considered bad form, however, and as many have pointed out already, you should use a hash instead.

[ambrus]

Perldoc perlref specifically asks you not to call them "soft references". They're symbolic references. Just like in unix, you have hard links and symbolic links (symlinks).

[cool_jr256]

Hope I understood your question...

$names[1]="sam";

That would replace "bob" with "sam" in the array.. but then again it's so hot in my office my brain is going crazy..

[omega_monk]

This would work if the array was an array of var names, but the OP has them as just strings..

[dReKurCe]

Greetings:
The following code uses refs to access the scalar variables:


our $file1 ="tom";
our $file2 = "bob";
our $file3 = "joe";
my @names =( "file1", "file2", "file3" );
$ref=\@names;
$file=$ref->[0];
print ${$file};