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Re^2: What causes HASH to print?

by Thelonius (Priest)
on Feb 27, 2007 at 16:32 UTC ( #602326=note: print w/ replies, xml ) Need Help??


in reply to Re: What causes HASH to print?
in thread What causes HASH to print?

If you have "use warnings;" in your code (or run with "perl -w"), you should get the warning:

Reference found where even-sized list expected
If you don't have "use warnings;", then put it in before asking a question. The warnings are there to help you, not annoy you.

UPDATE: And, if the warning is a little obscure, which in this case it is if you haven't seen it before, you can also "use diagnostics;". For example, perl -Mdiagnostics -w pm602312.pl gives:

Reference found where even-sized list expected at pm602312.pl line 2 (W misc) You gave a single reference where Perl was expecting a list with an even number of elements (for assignment to a hash). This usua +lly means that you used the anon hash constructor when you meant to use parens. In any case, a hash requires key/value pairs. %hash = { one => 1, two => 2, }; # WRONG %hash = [ qw/ an anon array / ]; # WRONG %hash = ( one => 1, two => 2, ); # right %hash = qw( one 1 two 2 ); # also fine


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