CODEWITHSUNDEEP
perl
tylerjw
tylerjw

Reputation: 770

I defined a hash, but exists function throws an error saying it's not a hash

This problem seems to be one of scope. The line with the exists function on it throws an error saying that it's not receiving a hash as an argument. How can I make so the value being passed to the exists function is my hash?

#!/usr/bin/perl

use warnings;
use strict;

open FH, 'test_out' or die $!;

my %pn_codes = ();

while(<FH>) {
    if(/.*PN=(\d*)/) {
        my $pn = $1;
        if(exists %pn_codes{$pn}) {
            print($pn, "exists");
        } else {
            %pn_codes{$pn} = 1;
        }
    }
}

Upvotes: 1

Views: 3532

Answers (2)

Miller
Miller

Reputation: 35198

You must specify exists on a scalar $hash{key}

if (exists $pn_codes{$pn}) {

However, you're essentially creating a %seen style hash which can be simplified to just:

while (<FH>) {
    if (/.*PN=(\d*)/) {
        my $pn = $1;
        if (! $pn_codes{$pn}++) {
            print($pn, "exists");
        }
    }
}

Upvotes: 3

mpapec
mpapec

Reputation: 50637

perl diagnostics can be useful,

perl -Mdiagnostics -c script.pl
exists argument is not a HASH or ARRAY element or a subroutine at c line 13 (#1)
    (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

Uncaught exception from user code:
        exists argument is not a HASH or ARRAY element or a subroutine at c line 13.
 at c line 13

Upvotes: 1

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