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PODeleting and adding Hash and Array references in Perl
 

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  1. PODeleting and adding Hash and Array references in Perl
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    <p>Continuing on from my <a href="https://stackoverflow.com/questions/4558981/dynamically-recursively-building-hashes-in-perl">previous question</a>, I ran into another problem down the road. I realized not only should there be hashes within hashes, there can also be arrays within hashes. So the paths would be something like </p> <pre><code>one/two/three one/two[]/three one/two/four one/two[]/four </code></pre> <p>i.e. the hash is supposed to contain the array will always have a <code>[]</code> as its suffix. According to the script I'm using (slightly modified version of the answer of my previous question), the above paths would result in: </p> <pre><code>one =&gt; { two =&gt; { three =&gt; "", four =&gt; "", } two[] =&gt; [ { three =&gt; "", four =&gt; "", } ] } </code></pre> <p>The script I'm using is: </p> <pre><code># !/usr/bin/perl use Data::Dumper; sub insert { my ($ref, $head, @tail) = @_; if ( @tail ) { if( $head !~ /^(.*)(\[\])$/ ) { insert( \%{$ref-&gt;{$head}}, @tail ); } else { my %newhash = (); unshift(@{$ref-&gt;{$1 . $2}}, %newhash); insert( \%{$ref-&gt;{$1 . $2}[0]}, @tail ); } } else { $ref-&gt;{$head} = ''; } } my %hash; chomp and insert \%hash, split( '/', $_ ) while &lt;&gt;; print Dumper %hash; </code></pre> <p>What I'd like to do, is once I find <code>two[]</code>, I'd like to delete <code>two</code> and add it to the array of <code>two[]</code> (if <code>two</code> exists) and then rename key <code>two[]</code> to <code>two</code>.</p> <p>So the end result would look something like:</p> <pre><code>one =&gt; { two =&gt; [ { three =&gt; "", four =&gt; "", }, { three =&gt; "", four =&gt; "", } ] } </code></pre> <p>So I tried adding checks within the <code>if else</code> for checking keys with or without <code>[]</code> suffixes but I got a range or errors like <code>[$variable] is not a valid HASH reference</code>, etc. How would one go about checking the type of the variable (eg <code>$ref-&gt;{$head} is array?</code>) and deleting and renaming keys of the hash efficiently? </p> <p>Thanks. </p>
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    1. USGaurav Dadhania
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    1. COSeems to me it's hard to build something simple and consistent if you can get both `two` and `two[]` at the same level.
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    2. COYup, `two` and `two[]` will always be at the same level and can occur in random order eg(`two`, `two[]`, `two`, etc. (that's how I got the hash reference error as I had already renamed `two[]` to `two` and encountered another `two`))
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      1. USGaurav Dadhania
    3. COSorry, I still don't see how that structure is being constructed. Could you trace its contents after each line is processed, with explanation of why the changes happen there?
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      1. USJB.
 

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