Hi,

welcome to the monastery, :)

That's because Perl has two forms for each variable type, and you are implicitly using both for hashes:

Using strict would have warned you that you didn't declare two different variables %hash and $hash beforehand.

See perlreftut *

Background for this "dualism" is that references were only introduced with Perl5 and the old Perl4 syntax was kept compatible.

Furthermore does Perl need context, the $ upfront denotes scalar context.*

Edit

Demo in the debugger

~ $ perl -de0

...


  DB<4> $hash{key1} = 'val1'  # add scalar to %hash

  DB<5> say %hash             # list form
key1val1

  DB<6> x \%hash              # dump
0  HASH(0xb400007063b64e70)
   'key1' => 'val1'
  DB<7> use strict; $hash{key1} = 'val1'
Variable "%hash" is not imported at...

# versa

DB<8> $hash->{key2} = 'val2'     # add scalar to $hash

  DB<9> say $hash                # hash ref
HASH(0xb400007063ceb198)

  DB<10> x $hash                 # dump
0  HASH(0xb400007063ceb198)
   'key2' => 'val2'
  DB<11> use strict; $hash->{key2} = 'val2'
Variable "$hash" is not imported at

[download]

Cheers Rolf
(addicted to the Perl Programming Language :)
see Wikisyntax for the Monastery

*) updated

In reply to Re: Hash syntax by LanX
in thread Hash syntax by mvanle

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.