in reply to unshift single scalar

If I understand correctly, you want:

unshift (@output, "Top");

The array that you want to alter should be the first argument to unshift.

Update: Added explanation.

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Re^2: unshift single scalar
by Bodger (Acolyte) on Aug 09, 2014 at 18:47 UTC

    I saw that in the docs but it did not explain what it was, but it says this:

    Starting with Perl 5.14, unshift can take a scalar EXPR, which must hold a reference to an unblessed array. The argument will be dereferenced automatically. This aspect of unshift is considered highly experimental. The exact behaviour may change in a future version of Perl.

    But that is a winner, it works.

[reply]

      No. When the docs say 'unshift can take a scalar EXPR', they mean as the first argument, eg:

      my $ref = [ 2, 3 ,4 ];
unshift $ref, 1;

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      But that's probably too much information. What you need to understand is that the standard (non-experimental) syntax for unshift is:

      unshift ARRAY,LIST

      It so happens (as is often the case) that the LIST that you want to add at the beginning of your ARRAY consists of just one element (namely 'Top').

      Maybe the doc for unshift could benefit from a less obscure example of usage?

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