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

Hi Monks,

I tried the string convert to hash in the following format.

$string="1:one;2:two;3:three";
%hash=(1=>"one", 2=>"two", 4=>"three");

I wrote the code below, but not getting the above hash. Kindly let me know what is the issue, and solution. 

use Data::Dumper;

%hash =     (split /\:/,  (split /;/ $string));
print Dumper \%hash;

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now getting output is:

$VAR1 = {
          '3' => undef
        };

[download]

Replies are listed 'Best First'.
Re: Split string into hash
by davido (Cardinal) on Feb 10, 2011 at 06:30 UTC

    You don't have to split twice. Perl is smart enough to know how to load a flat list into a hash. 

    use strict;
use warnings;

use Data::Dumper;

my $string = "1:one;2:two;3:three";

my %hash = split /[;:]/, $string;

print Dumper \%hash;

    [download]

    The output is: 

    $VAR1 = {
    '1' => 'one',
    '3' => 'three',
    '2' => 'two'
    };

    [download]

    No guarantees as to the order, as hashes aren't sorted.


    Dave

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Re: Split string into hash
by andreas1234567 (Vicar) on Feb 10, 2011 at 06:19 UTC
    Your code contains syntax errors, and had you used warnings you would have gotten some hints on what is wrong. I would do something like this: 
    $ perl 
use strict;
use warnings;
use Data::Dumper; 

my $string="1:one;2:two;3:three";
my %hash;

my @list1 = split /;/, $string;
foreach my $item(@list1) {
  my ($i,$j)= split(/:/, $item);
  $hash{$i} = $j;
}
print Dumper \%hash; 
__END__
$VAR1 = {
          '1' => 'one',
          '3' => 'three',
          '2' => 'two'
        };
$

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    --
    No matter how great and destructive your problems may seem now, remember, you've probably only seen the tip of them. [1]
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Re: Split string into hash
by Anonymous Monk on Feb 10, 2011 at 06:20 UTC 
    %hash = map{split /\:/, $_}(split /;/, $string);

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Re: Split string into hash
by chrestomanci (Priest) on Feb 10, 2011 at 11:11 UTC

    We had almost the same homework question yesterday.

    This one at least shows some effort to solve the problem, but I do wonder where the question comes from.

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Re: Split string into hash
by locked_user sundialsvc4 (Abbot) on Feb 10, 2011 at 15:00 UTC

    Obviously some University or trade-school out there is in its fifth week of classes ... and full of lazy students.   (I have been a college professor, so I can say that.)

    Nevertheless, I would caution that when dealing with “real” data, it isn’t enough to simply write code that works perfectly when given correct data, but that behaves unpredictably at all other times.

    #define SOAPBOX
    • Data will contain errors and inconsistencies, and the only player that can detect them is:   the computer itself.
    • If the computer detects that it is in a situation where it cannot meaningfully continue, it should not allow itself to continue.
    • Only the computer can make that determination.
    • If the software does not aggressively test its data, it is usually impossible to determine whether the problem is with the software or with the data or both.
    • Per contra, if it does do so, it becomes impossible to assert that the input data does not contain the issues that are being tested for ... a very important thing to be able to say in a real-world production setting, where hundred-megabyte input files are common.
    #undef SOAPBOX

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