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printing hash produce errors

by Xfiles (Initiate)
on Jun 02, 2013 at 12:06 UTC ( [id://1036580]=perlquestion: print w/replies, xml ) Need Help??

Xfiles has asked for the wisdom of the Perl Monks concerning the following question:

I am trying to execute the following line of code : 
#!usr/bin/perl


use strict ;
use warnings ;



my %hash = {'perl' => 1 , 'C' => 0} ;
foreach my $key(sort keys %hash)
{
     print "$key : $hash{$key} \n" ;

        }

[download]
but it gives me the following error : 
Reference found where even-sized list expected at perl.pl line 9.
Use of uninitialized value $hash{"HASH(0x98bf7ec)"} in concatenation (
+.) or string at perl.pl line 12.
HASH(0x98bf7ec) :

[download]
so what is exactly the problem ?

Replies are listed 'Best First'.
Re: printing hash produce errors
by bart (Canon) on Jun 02, 2013 at 12:18 UTC
    Your problem is that you're mixing up hashes (%hash) with hash references ({ key => value }) -- note the braces.

    Replace the braces with parens and it should work: 

    my %hash = ('perl' => 1 , 'C' => 0) ;

    [download]
    This produces a flat list, not a hashref, which is exactly what assignment to a hash wants.

    Alternatively you could use a hashref (= a scalar pointing to a hash) everywhere: 

    my $hash = {'perl' => 1 , 'C' => 0} ;
foreach my $key(sort keys %$hash)
{
     print "$key : $hash->{$key} \n" ;

        }

    [download]
[reply]
[d/l]
[select]
      that's it , thanks .
[reply]

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