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Perl Language Reference Manual
by Larry Wall and others
Paperback (6"x9"), 724 pages
ISBN 9781906966027
RRP £29.95 ($39.95)

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%s argument is not a HASH or ARRAY element or a subroutine

(F) The argument to exists() must be a hash or array element or a subroutine with an ampersand, such as:

$foo{$bar}
$ref->{"susie"}[12]
&do_something
ISBN 9781906966027Perl Language Reference ManualSee the print edition