Firstly, to correct the record, the exists function can be used on arrays to test the presence, defined or otherwise, of an array element.

As of Perl 5.6.0, the exists function can be used on arrays to test the existence of an element within an array. For example:

my %hash = ( 'key' => 'value' );

print "exists \$hash{'key'}\n" if exists $hash{'key'};

my @array = ( 'value' );

print "exists \$array[\$index]\n" if exists $array[0];

[download]

Under Perl 5.005.03 this code results in an error:

exists operator argument is not a HASH element at test-5.00503.perl li
+ne 7.

[download]

Whereas, under Perl 5.6.0 or later, the code executes without error:

exists $hash{'key'}
exists $array[$index]

[download]

As such, your solution here will be to employ a newer version of Perl, rewrite your code to use the defined function as suggested by the other posts in this thread, or check your index against the value of $#exp (the index of the highest array element).

 

perl -e 'print+unpack("N",pack("B32","00000000000000000000000111101000")),"\n"'

In reply to Re: exists and defined functions by rob_au
in thread exists and defined functions by arrow

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