Adding Hash Keys/Values

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

Dear Monks, I am in need of a fix for the following. I need to append to the hash as shown. How is this done?

#!usr/bin/perl
use strict;
use warnings;

my %table_hash = (
        '0,0' => 'X',
        '0,1' => 'Y',
        '0,2' => 'Z',        
);
print join ",",%table_hash,"\n";
my $n=0;
my $m=0;
foreach $n (0..3) {
    $table_hash{'$n,0'} = $m;
    $m++;
};
print join ",",%table_hash,"\n";
[download]

Comment on Adding Hash Keys/Values Download Code

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Re: Adding Hash Keys/Values by kennethk (Abbot) on Nov 08, 2012 at 15:57 UTC
The answer to your immediate issue is that you need to use double quotes instead of single quotes if you want a variable value to interpolate into a string. Your line should therefore read `$table_hash{"$n,0"} = $m;`. See Quote and Quote like Operators in perlop. You are using compound keys to emulate a multidimensional array in your code, which is very Perl 4. With the addition of array references (a couple decades ago), I would do this with something like: `#!usr/bin/perl use strict; use warnings; use Data::Dumper; my @table = ( ['X', 'Y', 'Z'], ); print Dumper \@table; my $m=0; foreach my $n (0..3) { $table[$n][0] = $m++; }; print Dumper \@table;` [download] See perlreftut. #11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.	[reply] [d/l] [select]
Re: Adding Hash Keys/Values by Kenosis (Priest) on Nov 08, 2012 at 15:56 UTC
Use double-quotes so `$n` is interpolated: `$table_hash{"$n,0"} = $m;` [download]	[reply] [d/l] [select]